i would strip all the paint off the engine compartment it was more than likely rattle caned there are sometimes compatibly issues with the new paint you have the engine out do it right the first time
sounds like vapor lock .check all of the above first . if that doesn;t work what i did was put a 440 fuel lines it comes with a return line you will need to also buy the vapor separator 440 fuel pump and 440 fuel pickup that goes in the tank that cured that problem
mine is a1971 383 car it did not come with a fuel separator the 440 and 426 cars did so i bought a 440 fuel line set up that cured the vapor lock and i put a filter between the separator and the carb
i would replace it who knows what junk and rust is in it .sometimes after running the carb float valve will leak a little allowing fuel to over flow the carb flooding the engine that separator bleads the pressure out of the fuel line so that won;t happen
to get max caster the upper ball joint needs to be as far back toward the fire wall as you can get it and still have good camber.. it;s best to.lift the wheels off the ground suspension hanging when adjusting the cam bolts
it has hydraulic lifters they pump up from the oil pressure when the engine is running .. when the valves are fully closed you can wiggle them a little that is normal if it doesn;t clack when running you are good to go