Disappointed magnum head flow numbers....

I doubt it.

My 388" 360 based race motor started life with ported w-2 heads flowing 294 cfm intake, 13-1 compression on alky, 750 Holley DP, dizzy locked at 36 degrees, Crower solid lifter cam 580/580 with a 260 degrees duration @ .050... 575 HP @ 6,000 rpm.

Now I'm shooting for 625 with my 850 carb, more cubes, lighter valves and a better cam. Still might not make it...
I think he is including a 150 shot in those numbers.