Pop pop on exhaust side

I can tell you that your idle timing is too much, and the sooty plugs are the proof.
The only thing keeping that engine running is the multi-strike box.
I can run that cam at 5degrees, and cure that sooty problem right up.

Here's how it works;
you buzz the timing up, and the rpm goes up with it. So you close the throttle with the speed screw. Now the engine runs out of idle fuel from the transfers, so you richen up the idle mixture screws and Voila, you get a nice idle.
The problem is
As soon as you open the throttle, and the transfers come on line, the AFR goes rich, and the plugs get sooty, and it's rich all the time

Here's the cure;
Reset your mixture screws to 1/2 turn out. leave them there.
set your idle timing to not more than 12*, and leave it there.
set your idle speed to, in the window of 550>650, in gear, wherever it idles best.
Put the trans into N/P and make sure the idle speed has not increased more than ~100 rpm. If it does, then the engine is making too much Idle-power.
The cure is less idle rpm, or less Idle timing.
If the in-gear idle was at the top of the window, try 50 rpm less.
If the idle-rpm was already on the low side, then take out 2 degrees of timing, and reset the idle-speed.

>Your engine will make the most sub-stall rpm power, with the idle-timing maxed out. This could take up to around 30/35 stinking degrees. But you cannot drive it like that on the street. The car will be very difficult to drive at low rpm.
Your engine can be adjusted to idle just fine down to 5* advance, maybe even less.
>Your engine does not car about how many inches of vacuum it idles at. As to vacuum, the only things that are important are that the number is stable, as in not drifting up and down, and that it appears to be more or less glued in one place.
>Your engine does not care what the idle-timing is, anywhere in between those two numbers. The only thing that changes when a 220ish cam is used, is the idle/off-idle power. So you have full freedom to set the timing anywhere in that window, until it soots up the plugs or becomes hard to drive or bangs the transmission when you put it into gear.
>Your engine, the first time it cares about timing, is at stall rpm. And the second time it cares is after about 3400rpm.
To make the throttle opening exactly right, for that cam, if you care to know, is;
Take the carb off, and flip it upside down. Then with the speedscrew, set the throttle opening to reveal the transfer slots open to about exactly square, but not less than. After this, do not move that speedscrew. Now, flip the carb upright and set the mixture screws to 1/2 turn out. If your carb has a 4-corner idle system, close the secondaries up tight but not sticking, and close the secondary mixture screws; your #703 cam does neither need nor want that system to be operational. If you need to relax your link-rod to make this happen then do it. Reset all your accelerator pump parking spots as may be required. Reinstall the carb, fill it up and start the car.
DON'T TOUCH ANYTHING
Let the engine warm up, then retard the timing, without looking at the timing marks. Use the timing to get the rpm down to 750, then put the trans in gear. if the rpm drops more than 100 or the transmission bangs, then readjust the timing for 700 rpm in neutral and try it again. and so on.
If the rpm falls to less than 550 in gear, STOP retarding the timing.
If the idle-timing falls to less than 10 degrees, Stop there.
Go check your WET fuel level;
If it is at spec or higher, reduce it about a mm or 1/16 and restart the test.
If it is below spec at least 1mm, leave it there.


The above assumes that ;
1) the PCV is correctly plumbed and functioning correctly
2) that the oil-level in the pan is below the crank
3) that the fuel level is stable
4) that all the air that the engine is getting, it all came past the transfer slots.
5) that engine coolant level is at least 180* and is stable
6) that the convertor is 100% ok.
7) that the fan is not disrupting the bowl vent.
8) that fuelTank is properly vented
9) if you have a vapor canister, that it is functioning properly
10) if you have electric fans, and your engine coolant temp is jumping back and forth 30 or 40 or more degrees, I can't help you.

BTW
the condition of those plugs make them junk.
Get some Champion coppers in a heat-range of 12. I forget the number; maybe RJ12YC/something like that, with a 5/8 hex for header clearance. but 12s.