Gentlemen,
My opinion....
How about a Carter AVS (NOT the Edlebrock AVS not a true copy of the original AVS design) for 1970 375 HP 440. OR a Carter # 3705sa, as used on the Stage 3 MaxWedge (750 -780 CFM). This is the one with 1-11/16" primary AND secondary throttle bores and the adjustable secondary air valve. The original AVS design would need to be slightly mofified to eliminate the off idle air bleed circuit (which was created for emission requirements and caused lean an off idle stumble) and POSSIBLY increasing (by 0.001" - 0.002") the idle feed restrictions, located in the primary booster venturii.
It seems as if everyone wants to use either HOLLEY or EDLEBROCK.....not sure why? The 440 / 375 hp engine's OEM Carter will flow approximately 750 - 800 CFM @ 1.5" pressure drop AND have the adjustablity of the secondary's air valve.
It seems as if everyone likes to run too much carb without any consideration for mixture velocity (from idle thru wide open throttle response)....the faster the velocity the better.
Everyone knows that the next door's neighbor's brother-in law's cousin's best buddy is the definitive source for carburetor (as well as just about everything else) unsubstantiated information, sort of......but this is just my opinion.
Bob Renton