I called summit asked them to send me the new proform carb main body replacement. I asked for the 650 because everything in my body and everything I know (that's not saying much) says that a 750 is too big. Here's the kicker. They don't make the 650 yet. Summit sent me a 750. I have a 650 double pumper holley now. Do I mill the choke horn and drop in downleg boosters and call it a day? Or try to get away with the proform which is the 750. Now I have a RPM AIRGAP gasket matched to a set of AFR 185's with a x-303 cam and about 9.5to1. It's getting sqeezed so it's got a 1/2in spacer more or less. But I want to keep the dual plane. The dual plane is why I think I might be able to keep the 750. OH I spin it to about 6500.