If the air/fuel mixture screws are out only a 1/2 turn you are rich on the idle circuit. So you can either decrease the size of the idle feed restricter or make the idle air bleed bigger.
If your engine is as stock as you say, then I doubt you have the throttle open too far at idle. You need to pull the carb off and flip it over to verify that the transfer slots are .030-.040 exposed. There are plenty of threads in the fuel systems forum here.
I would stop playing with the secondary opening until you get all the primary side issues cleaned up.
Set your power valve opening by CRUISE vacuum and NOT idle vacuum. For example, if you have 18 inches of cruise vacuum you need a 14.5 power valve. Sadly, there is no such thing. You may find a 12.5 power valve if you get lucky, but AFAIK, they haven’t made those in years, so a 10.5 is the best you can do.
Before anything else, add some initial timing to it. Just don’t get the total any higher that what it should be. You may have to recurve the distributor to get that correct.
If this carb is like all the rest of them (no reason to think it’s any different) then they are sent out dead rich everywhere. You just have to tune them.
I also forgot to mention the correct way to tune the primary side is to get the main jet as lean as possible without a lean surge. Then leave the primary main jet alone. If you are lean (or rich) at wide open throttle you need to change the size of the power valve channel restricters, which are the holes you find when you remove the power valve.
If the carb doesn’t have changeable jets in there, you can use 6-32 brass set screws in the holes and you just drill the brass with the hole size you need. Of course, you’ll need a tap and the correct drill, plus a pin vise and a set of 80-61 number drills. It’s easy when you get the hang of it.
Again, all this and more is covered in several threads over in the fuel systems forum. It’s worth looking at them if you really want to tune your carb for the best fuel efficiency and power.