Hello Andrew
In very round figures, at 6000 rpm the 302ci is pumping about 525cfm, about 612cfm @ 7000rpm.
(1 cfm = 1728cim)
The Holley recommendation therefore appears to correct (as you'd expect).
When it came time to replace my aged and wobbly 700 double pumper I looked at the cost of refurbishing myself against a factory refurbished carburetor and decided that with the state of my carburetor and the number of things I wanted replaced - getting a refurbished carburetor was cheaper.
Holley has an ebay store where they sell factory refurbished carbs, I bought one, it arrived looking new and it has worked very well after a bit of tuning.
http://stores.ebay.com.au/Holley-Performance
Your main choice will be between vacuum secondaries or a double pumper.
There are some nice 600 double pumpers or vac secondary 4 barrels currently listed that I think would suit nicely.
Personally I would keep it simple and get something like this:
Holley 0-4776S 600CFM Shiny Double Pumper Factory Refurbished 4bbl
If you're worried about the fuel economy then maybe look at the vac secondary equivalent.
Come to the AGM and talk carburetors
- you'll get plenty of input.
Apologies to all the carburetor gurus for the forgoing massive over-simplifications.
Good luck Andrew.
LoBelly