Heads, how much gain?

Brodex B1/BS. I believe the best direct swap head on the market? They will out flow the 452 at max port right out of the box. You put a decent port on them? Forget about it. The only problem is that one is going from an open 88cc chamber with the 452 to a closed 65cc chamber with the B1s. This WILL significantly raise compression. Obviously cannot run with any domed style piston that I know of. Even flats at near zero deck will most likely get you past 91 octane use.