Which Carburetor???

There are lots of calculators out there that will tell you how much air is required to support a given displacement, rpm and volumetric efficiency. Here is one; http://www.csgnetwork.com/cfmcalc.html

An engine never uses as much are as people think and for a street car you want to pick a carb that will be correct for the rpm range the engine will operate in the majority of the time. People always tend to over carb their engines. If you car is primarly a street car something in the 650 to 700 range will be more than adequate.