I'm sure this topic has been beaten to death then revived and beaten again. I have a BBC 476, aluminum oval port heads,roller cam .580 lift, dual plane intake, 9-1 compression, center rise exhaust. I'm getting rid of my 830, putting on a marine carb. I'm also switching to an AA impeller, trying to keep rpm's at 5000 or lower.
Choices: I have a reman.750 Holley dp marine sitting in the garage, run it as is and jet accordingly. OR have that carburetor rebuilt by the carb shop to get everything out of it possible. OR get a brand new 850 quick fuel, they seem to be the best brand new choice for a marine carburetor.