512 build

Those mid-60s Bs are tough. I'd go with the M1 single plane. It wil lgive up a little but not as much as the RPM on that combo. The Indy is another good choice but I know the M1 fits - not sure of the Indy. I had a 440 in in a '67 GTX that had to run the M1 and stock air cleaner to fit under the hood. I haven't tried the Indy but the FBBO guys would know.