Yes the fuel is going to percolate in a Carter style carb.
Is your crossover still open, block it, switch to an Alum intake AND the Holley carb , though an 850 is a little big unless you are running an 800 ebrock , I hope you don't have the POS performer 750 , if so drop in it the bottom of the everglades.
My friend has a 383 I did for him last year , runs what I outline above with the cheapest , crappiest, gas he can afford and no issues.
for the most part except my 600 eddie carb sits right on my victorjr 340 intake with only a gasket and has never boiled the fuel, even E10 I buy out of town.
But the reason I think is the intake nor the eddie heads have heat risers so my carb has run fine in super hi heat in Vegas and Reno at over 110° with no problems. Even re starts are normal and no struggle in hi heat.
Block those heat risers in the heads and use a aluminum intake with no heat risers=electric or manual choke. Man those eddie heads are nice because of that feature alone IMO.
