[wkooiman]

I would expect that we've all seen the explanations about A-curve, B-curve, wheel HP, net/gross, etc.

If you consider that the 425 HP quoted for the 427 was A-curve (no accessories, no full exhaust), I bet it was pretty accurate. At the wheels? 350 would be about right.

The same thing is true for the 427 SOHC with 616HP for 1x4 and 657HP for 2x4. These were the numbers they made during testing on the Ford dyno.