What size valve's are in the 71-72 head's 'are they straight plug or angled. If they are 2.02 head's they are definately going to be better. The 78 heads are probally going to be more like smog head's and the valve's could be smaller. In 78, G.M. was just starting to come back with some power for the Camaro's. Kind of rebounding from the emission's era. So the older head's might be better,if they're the right size for you.