I purchased a '57 Chevy that had a 600 cfm Edelebrock. The engine is a 1969 327 Chevell stroked and bored to a 355 with a mild cam. This is what I learned from the receipts from the previous owner and calling the engine rebuilder. The car ran great until you stepped into it. The fuel bowls are small and it would starve itself out of gas.
Since then I purchased and rebuilt a'69 Corvette Rochester Quadrajet. The quadrajet is a 750 cfm. I changed the primary spring to the lightest tension one available. I now have all of the power I would ever want without gas starvation and much improved gas milage. 8 mpg with the Edelbrock to 21 mpg with the Quadrajet on the highway.
The engine will only suck the cfm as mechanically possible. Using the Quadrajet the rear secondaries only allow what is necessary when the need is there.
My opinion, if possible, try using a quadrajet. The rebuild kits are available through your local parts store for as little as $19.95. I purchased my carb from the internet for about $25.00 and a new vacuum pot for $15.00. This is much cheaper than a new Edelbrock Carb.
