I should have 'explained' myself better.
It was the 'mind-set' in 1968, that if you 'swapped' on a set of
67' 440 'HiPo' Heads on a 68' 440, you would gain {20 to 25} Horsepower.
That was what Chrysler was 'promoting', with a gain in compression
of {+1.10}.
Bringing your 1968 '440' from 10.0 to 11.10 Compression-Ratio.
