So much for valve shrouding causing the end of the world.
I ran the flows on my bench with a 4.500 bore and a 4.250 bore.
Lift........TF w/4.500......TF w/4.250.....RPM, 4.500 bore 2.25/1.78
.100..........76/61............75/60...............76/60
.200........154/132.........154/131............164/130
.300........227/193.........223/190............224/180
.400........279/239.........274/230............276/209
.500........324/261.........314/246............318/237
.600........337/270.........329/262............333/254
.700........332/276.........333/270............346/267
This was the best flowing port in the first head I tested, the other three were very close.
Heavy duty castings, just a really nice head. If they are ever again available when I need more heads there is no sense buying anything else.