Diagnosing a Potential Fuel Problem

Set the fuel pressure regulator to 6 psi, re-set the floats to spec and then see what happens.

I bet the engine is too lean after start because the choke probably doesn't work correctly if there even is one.

Anything beyond that is tough to do remotely without some readings from something like a wideband.

When I had a holley it would take one quick pump and then immediately fire, but then again my choke worked. Sometimes you have to feather it slightly to keep it running if it's really cold but really anything without an exhaust crossover will be a little bit cold blooded.