what CFM would you use here

lol Bill. I had a buddy who used a 2 to 4 adapter on a smogger 2 barrel 383 with a 625 avs and he got serious bog when he put his foot in it. the same carb ran good on four barrel intakes. that's not to say it wont work on your 360, but that's the extent of my experience with them.
750s (1407eddys) seem to be rich out of the box , and with the adapter , it may end up being a mess unless you can lean it out. I know you hate holleys so I wont throw out the 4160 as an option LOL although I run one and I love the thing.