I'd go with pretty much my exact setup: Langdon headers, 2.5" single exhaust, Offy single intake (heated) and, the one thing I'd change, a 500 cfm carb.
With the set up Im running the calculators all say about 400 cfm but I can tell it's not enough.
I didn't go with any Clifford stuff just because of the price. dollar for dollar the route I went is just better. More power earlier in the curve, plenty up top, and all really bolt-on.
You're smart to get rid of the integrated head. Not so smart tto look at dual carbs. Too much of a PITA to tune. Stick with a single. You don't really gain anything with dual other than pretty looks.
Eventually I'll go with, probably, an Isky cam and head work but I'm pretty good power wise right now.
