Finally got some results on these from the customer but it doesn't really tell the whole story. The engine was chassis dyno'd before and after and according to the dyno, we put almost 100hp to the rear wheels, all things considered, but I know this is short of what's actually there.
These went on a 427 in a 69 Impala for a customer in NY with a FM ported Vic Jr and a Straub 3 lobe hyd. roller cam, and I also set the valve train up at my shop. The engine was wheel-dyno'd before the changes at 423 rwhp and the conditions that day were 67*, 13% humidity, 29.51 baro. The ported heads, intake and cam netted a gain of 65 rwhp with a best pull of 488 rwhp with conditions of 90.6* 33% humidity and 29.69 baro. On the first tesst they were also using a fan through the hood scoop which they said was worth 6hp; they didn't do that on this test. Given the differences in conditions I'd say we could be looking at possibly a "corrected" ~85 rwhp gain. That would be 508 rwhp X 1.2 = ~610 @ the crank. The problem lies in the fact that the dyno shows the engine peaking at 6200rpm and going pancake flat to 6900. We know for a fact that this engine is not making peak power at 6200rpm...more like 6800-6900 and closer to 670hp @ the crank. It's either a converter problem, or the tires are spinning, but none the less.
Click on the pic below and listen. This thing is pissed off!