You are correct with the 750CFM. I was thinking about a carb I was looking at on ebay when I wrote that. Eitherway, with a performer manifold for a 455 olds. there is no way to run the one I have with the divorced choke. In any event It's not giving me what I need/want, and I want to upgrade. Don't really care who disagrees since it's my ride. If anybody has the 770 Holley that I posted about that they want to move, get ahold of me.