Need to pick your brain here for a minute concerning the 516 heads..what is their basic cc in stock form, and I see you had 2.14/1.81 valves for your test,how important is the larger valve size say versus the 2.08 and say 1.74 exh in the same test..and on the 906's what would it take for them to acheive the same as the 516's in your test....wait...before you smack me in the head with a pistolgrip I have a buddy that has a 73 440 MH,cast crank 30K engine runs like new and I was gonna recommend this build to him and these are some of the ?? he asked me about,he does not have the 516's but has all the others[906,452,346's]and he has all the other components of your test[and others] and his pistons are .160 in the hole same as test...