I did a little test with my 440's. The first one was built with all out 906 heads. Full port, oversized valves. THe 2nd 440 was built with OOTB eddy RPMs. Literally OOTB... Identical builds except heads and 850 vs. 950 carb.
The 906's made tq 500 rpm higher (3500 vs. 4000) but peak hp 200rpm lower (5600 vs. 5800). Very similar power numbers and both cars run nearly the same number.
