318 2bbl won't idle without choke

The reason that I mentioned that you can run the engine with the top off, and the horseshoe shaped float-pin retainer pressed down,
is so you can see what the power-piston is doing.
If the manifold vacuum is too low, the piston comes up, and if there is enough signal in the booster, then it will begin dribbling.
My first response to that is to just grab the distributor and give it a bunch of advance,until it runs as smooth as it gets. You cannot hurt the engine by doing this, even if it gets up to 25 or 30degrees. Don't even put the light on it at this point. The increased timing will increase the manifold vacuum, and suck the power piston down;(BTW, there is no gasket under the power piston. If you put one there, the needles will go up, and make the entire system rich, and/or, the transition will be wrong from Idle to Part Throttle :: Ok, let me rephrase that; I have never seen a gasket there (just because I have never seen one there, doesn't mean that a model might have been designed to have one, I've just never seen one), and there is no point to put one there, and IIRC, the vacuum port comes in on the side of the bottom down there, and would be covered by a gasket, if you put one in there. If the port gets covered, guess what; Hyup, the power piston stays full rich.
Now, with the extra timing, you can idle it down, restore the transfer slot sync, and go find why it sounds like it has a horrendous air leak.
And finally, when you get that figured out, you have to put the timing back.

Furthermore, put a vacuum gauge on it.
It will tell you about the low vacuum, which could be caused by, in order of likelihood;
1) an air leak; base gasket or intake to head, power brake booster, broken PCV valve or it's hose, or even the vacuum take-off tree.
2) retarded ignition timing
3) retarded cam timing
4) intake valves not closing
5) plugged muffler
6) faulty exhaust valve(s)