magnum hds

I agree with Moper on the iron heads over the eddy's, but depending on 388's centerline and overlap on the cam will depend on weather the engine with detonate or not as cylinder pressure could fall off greatly depending.
As for flow #'s this is what we have come up with just doing bowl work and gasket matching, with a 2.02 valve and a 1.62 exhaust valve, and the exhaust was just bowl blended and no other port work and a good valve job on both sides.

lift I/E
.100 91/79
.200 177/119
.300 225/150
.400 245/193
.500 248/204
.550 250/207
.600 272/209
.700 272/210

Alot has to do with the type of valve used, finding the right valve is as hard or harder than the right head, this is why I do alot of remachining on valves to get what I need. Ferrea IMO has the best designs to start with.