what CFM would you use here

avs is like an air-valve type of carb. A bit more forgiving on the street. It uses a spring loaded flap above the throttle plates and no boosters on the secondary side. afb uses counterweights and boosters. avs was used on stock mopars from 68 to 71. either one is good but the avs is slightly easier to tune. It's a very good carb(AVS) but never got the recognition because everyone thought it was an AFB. It is a very good carb. I'd just use a performer intake and the avs.