sorry im slow still getting used to this forum, the layout, answering, etc.
yes shes healthy once rolling.
no its doesnt have the holes.
really not trying to run from the problem, but i think trying other carbs might work. just for the hell of it.
the more experienced guys at the track say a vac carb would be good
my q jet car was exact same issue, chased it for years, tightened that stupid flap and good to go.
apparently vac holleys are adjustable also.. with a spring kit i heard.
with the 750 on your higher compression big block 4 speed you mentioned, i feel like mines a little extreme for my dish piston 355