It depends on your proposed usage. My car is a RACE car. My Rochester Fuel Injection only flows around 600CFM. My engine combo probably makes horsepower above 7000rpm, but my intake restriction (Rochester FI) limits my .030 over 327 to just over 7000rpm. The calc shows that a 327cid engine pumps about 602cfm at 7000rpm, so for (say) drag racing when the engine speed never drops below 6000, and shifts are at 8000
you could benefit from a ram type or individual runner manifold and a 700cfm (or 750) carb. HOWEVER, for a street car, with daily drivability issues, and a 2000 to 5500rpm usable rev range (even for autocross or some mild competition events) a 600 or 650cfm carb on a torquer type manifold is about the most efficient combo, altho it loses some of the "cool factor".