Slant six 1920 stall

Ok maybe this;
after the lash is reset;
you must do a compression test, and do it correctly by, at WOT, cranking until you get two consecutive same or similar numbers on every cylinder. The results must be even or close to even, between all cylinders. I like numbers over 140, but if the cam is not stock, the numbers may not be meaningful, other than they must be even and reasonably high, which to me would be over 125.
I would do a LeakDown test to prove the valves are sealing; But you the compression test will do for now.
Now;
if you have a carb that looks like the one in post #7;
take the carb off, make sure the choke is off, then flip it upside down. Close the throttle completely with the speed screw. Then open it until the transfer slot is about square. If your cam is not stock, you can open it a tad further, say to a lil taller than wide. Flip it rightside up. Reset the mixture screw to 1.5 turns from lightly seated. Block ALL vacuum ports except the PCV and make sure that port is open.
After this, DO NOT Touch the speed screw again, until I tell you to.
Reinstall the carb, making sure the gasket is the correct one for both the intake and the carb. Pour some fuel, about 40/50cc into the float bowl thru the bowl-vent. Remove, or at least loosen, the gas cap.
Loosen the distributor hold down just enough so that you can rotate the distributor with some difficulty. If you still have points, set them to the factory spec (I forget what it was, guessing .019 or so).
Make sure the PCV system is working, including that the hose is rated for PCV and not collapsing under vacuum when it warms up.
Do not reconnect the Vacuum advance.
Ok
now, in a minute,
you are gonna start the engine and warm it up. If the intake is not sucking air somewhere, and if the valves are sealing, and if the ignition timing is close, and if the float level is correct and remains correct; then the engine will start right up and after a short warm up, it should idle in the ballpark.
If it doesn't;
and if the idlespeed is too slow, you will advance the timing until the idle speed is in the ballpark. If it will not speed up into the range of 550 to 600 in Neutral/Park; either the float level is very high and the carb is flooding, or the cam-timing is suspect.but
if the idlespeed is too high;
by only a couple of hundred rpm, you will retard the timing until the rpm settles down. But if the rpm us well over 800 rpm; the intake IS sucking air, or the carb is sending unauthorized air/fuel into the intake, or the cam-timing is suspect.
If the engine is hard to start after the fuel level is stabilized AND If you didn't do a LD test earlier, now is the time to do it...... because; If the exhaust valves are not sealing during cranking, the falling pistons on the intake stroke will suck air from the exhaust system, instead of air from the plenum. This air in the exhaust has no fuel in it so of course it will be hard to start.
It could happen that the valves are sealing but at the wrong time, so once again, that would point to wrong cam-timing.
As for ignition timing; the engine is not particularly fussy for timing during cranking, as long as it's not retarded or crazy-advanced. But the further it is from ideal, the more throttle it's gonna take to keep it running after it begins to fire. Retard is worse. But remember, I told you not to mess with the speed screw until I tell you to. and we ain't that far yet.

Ok, now you know what to expect and what to do if it don't do what you expect,lol;
so crank it up and fix the idle.Until you get the idle fixed don't bother putting it into gear and don't even think about driving it.
Your target rpm for neutral/park should be from 500/550 for a stock cam, to 700/750 for a big street-cam.

PS; I don't have specs on your cam. If you do, please post them up, so I can get an idea of where to go from here.