I've scratched my head over that one myself Sal, and questioned the numbers. George (Gessford) did some calculations with the specs on the motor and figured if it was running at 100% volumetric effiecency that horse power was possible. From the paperwork that came with the car I am inclined to believe the numbers (flywheel horse of course).
Going with 9.8 compression and milder cam George estimates I'll be giving up about 150 horse. I've heard it said the medium riser heads are "almost" as good as the high riser, but I wonder. You could drive a truck through the ports on my high risers.
The intake is a single plane 2X4 with full blown "race only" center squirter 660 Holleys. The engine was built "loose", I found out when I took it down. All clearances were at max. Like .005 on the piston clearance when .003 or so is normal. It also had the typcial oiling modifications done, etc. My feeling was this motor was built to race with a radical cam.
I can say this, it is/was the fastest replica Cobra on Island, 100 mph in 8 seconds!