pics please of your holley 1920 set up and linkage

Fuel percolation due to heat could be an issue, but if it does this without the engine running very long, like it seems in your case from your symptom description, then there was not enough heat to make this happen. However it IS a legit issue in hot conditions and on some engines; the earlier cars did not run as hot so I would not expect it as readily for your year car.

As for the torque, it needs to be very snug but not super tight. I can't give you a torque number. I looked up the max torque on a number 8 coarse thread screw and it was about 11 inch pounds but with the AL housing, I would go less. How did the stripped screw work with just adding the lockwasher? If the threads are stripped on the screws itself, go to the hardware store and get a new one....simple.

Can you explain this: "there was still a drip of gas coming out of the center blades in a continous steady slow drip." What do you mean by 'center blades'? Can you describe better where you saw the gas dripping out? If need be, crank the engine over for a while and then look down the carb throat with a mirror while holding the choke palte open and let us know where you see the gas coming out.

Did you replace the economizer valve, which is the plunger and diaphragm under the triangular cap held down by the 3 screws on the top of the carb. (See the forward left of the carb in my center pix.) If not, then the carb kit is just so-so. This could cause the carb to run continuously rich under all conditions except WOT.

The problem is still most likely the needle and seat, or the float being gas-logged. Get the list number off the side.

BTW, have you done any diagnosis on the car to see if you have good spark? My engine would always fire, even with the gas leaking into the manifold, so some tests of the spark system are in order, especially with the age and sounding like it needs work. Take off the spark wire from the center of the distributor cap and lay it with about a 1/4" gap to the engine metal; crank the car and see if the sparks will jump this gap with a mostly blue spark. If not, then the ignition system needs work first.

Has the car sat for a long time before you tried to get it running?