Just curious, any possible bore clearance issue with the 2.08 intakes on the 4.030 inch bore? Probably not when keeping the lift under .500. That's one heck of a cylinder head, though...
I would use the 915s if they are fresh, on the flat tappet motor, cause tyou have em. I would wait for the sale, and get the cnc speedmasters, bare, for the roller motor.
I would not put a lot of money into (most!) iron heads. There are exceptions.
