Eddy 1407

This is all messed up.
-Its time to check your true timing and then,the Transfer-port sync.
-The timing must be proven first. So prove the TDC mark on the balancer, using the piston stop method. If the timing is inadvertently a little over-advanced, the idle speed goes up.Then the cracking screw is backed out, messing up the T-port sync.
If your transfer ports are under-exposed, it may be because the engine is drawing air under the blades at the throttle shaft, or under the secondaries. This often makes the rpm increase and the carb, lean, especially if the PCV is not working correctly.The usual compensation is to decrease the curb idle screw opening to decrease the idle rpm, and perhaps increase the idle mixture setting and the result is the high idle; which cannot be reduced by the cracking screw without shutting the transfers off which results in a stall. So the idle speed ends up high.Then when you put it into gear, the TC drags the rpm down, and the lack of fuel in the leaking air,causes the carb to go lean; resulting in a stall. If this is your case, you will have to pop the carb and get eyes on the sync. The T-ports should appear as little squares to perhaps a wee bit rectangular.If your T-shaft/base plate is as worn as you say it is,then it may be impossible to get this properly set, and that will require either a repair kit, or a different baseplate, or a replacement carb.
-Next, make sure your pump is not sucking air. If its delivering air-bubbles into the bowls, that can be troublesome for the floatvalves.
-And lastly, I would do a cylinder leakage test. If the valves aren't closing you will never be able to tune it.
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But OP, If your T-ports are over-exposed, this is usually for one of two reasons;
1) the timing is retarded, or
2)there is a lack of idle air bypass.
So,again, prove your timing mark and timing. And then,make sure your PCV and hose are working correctly.This is the primary source of idle air bypass.The carb is calibrated to have a working PCV bypass air. If you dont have one, or yours is not functioning correctly, the curb idle screw will have to be opened to compensate for the lack of it. This will introduce syncing errors.
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-And while a sloppy clearance between the throttle-shaft and baseplate is not good, it is,often, tune-outable at idle. It may affect the idle consistancy if the blades do not park in the same place every time. The baseplate can be re-bushed. But if the shaft is worn out also, then maybe, (as I don't recall if they still make replacement shaft-kits),its time for a replacement.And if you really do have 1/8 inch vertical play, well then thats a whole lot of play. But I would suspect this leak as the source of your woes, only if your cam is stock or very near to stock, causing the first, under-exposed T-ports, condition.
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Here follows my tuning strategy for bigger than stock cams.The biggest cams I have tuned are 250*@050. If someone reading this has a bigger cam than this,I think it would still be a good starting point.

Bigger cams need lots of idle air bypass If you give it air by cracking the curb idle screw, the blades open and expose the transfer ports, and also expose the sparkport, which, if it's hooked up will/may bring the advance in . Then the rpm goes up from the additional advance,and the A/F goes fat. Which with no load on it may work. But when you put it into gear the TC drags the rpm down and the fatness floods the engine, and the timing drops out due to loss of signal, and maybe the engine stalls.
-So then,heres what you do; Give the engine the air it desperately wants,from some other non cracking-screw source, and dial in some serious idle timing.
-Put a new PCV on it with a proper non-collapsing PCV hose.Next crank the dizzy til the rpm stops increasing.Never mind the number for now. Next put a vacuum gauge on the sparkport and close the curb idle screw until the gauge reads 4 inches or less. Then if the rpm falls below target(bigger cams require a slightly higher idle speed ), give the engine some air elsewhere to get the rpm back up. Then close the primaries some more to drop the gauge reading closer to zero, and give it more air at the somewhere-else source, to get the rpm back.You will need to re-adjust the idle mixture screws as you go.Make sure the M-rods are down and stay stuck down(or the PV stays closed). Pull the springs out if you have to.
-Now; about the auxiliary air source.How about cracking the secondaries?This will generally pull the rpm up. If you cant get the rpm down, back up the timing.
-This method has never (On cams of 250* or less) not gotten me close. Sometimes I fine-tune with the float level. This method assumes that there is no vacuum leak between the intake and the head, that there is/are only minor vacuum leaks elsewhere, that the valves are fully closing,that the EGR,if equiped, is properly blocked, and that the float valves are able to do their jobs of maintaining a constant fuel level.

-Its very important to sync up the transfers and the sparkport.If you cannot crack the secondaries to give the engine the air that it wants, you will have to deliver air under the blades, some other way. One way is to provide a continuous PCV. Another is to drill small holes in the primary blades.This bypass air needs to be from a filtered source,obviously. Cracking the secondaries is common,and usually,easy.
-Now,once you are in the ballpark, and have learned what the engine likes, put a timing lite on it and see whats what. If its less than about 20*, well then, thats in the ballpark too.But if its more, back it up to 20* and increase the bypass air to bring back the idle speed.This assumes the TDC mark is true.
-Next put the tranny in manual low. With a stock TC, the idle rpm might come down 100 to 150 rpm, so we're looking for minimum 700/750 rpm. If the engine stalls from lack of rpm,try a little more bypass rpm, or a tad more cracking-screw rpm, or get a looser TC.If you have a really big cam, you'll need a higher stall TC anyway.
-Now, keep in mind, the curb-idle screw has an adjustment range, and does not have to absolutely remain with the T-ports fixed at square, to a wee bit rectangular. Once everything else is ballparked, I revisit this adjustment. This is what I do;
First I am going to fiddle with the curb idle screw, so I need to figure out a way to get back to the current setting. So I back out the screw to a point where the screw actually comes off the arm, and the blades are completely closed. I count the turns required to achieve this zero-point, and write it down. Then I put it back where I found it.Then I get in and put the tranny in gear, and attempt to drive,gingerly,away, and note how it reacts to very minor throttle inputs centered around the tip in point. If you get a sag at tip-in,or the engine seems to want to stall when you lift off the pedal; try a wee bit more Tport exposure.If the engine seems to be gas-pedal touchy, try a little less exposure. These are minor pedal changes, and must not be confused with accelerator pump problems.When you find the sweetspot, back out the curb-idle screw again to the zero-point, counting the turns, and write it down as a final number. Then return the screw to its former adjustment.This "final" adjustment can be fudged in the coming weeks, as you become familiar with the engines personality. Since you have written down the adjustment, it will be easy to get back to, should you get lost. At some future point, if the idle speed needs adjustment, but you have determined the curb-idle sweetspot, you may need to adjust the idle-air bypass instead.
- It really ticks me that modern performance carbs don't come with an idle-air bypass screw.
-Oh dont forget to limit your power timing, to put the springs back under the M-pistons,and to reconnect the vacuum advance and tune it's cut-in point.
- This has always worked for me. I hope it works for you.