I'd think for the stret especially w/ the aluminum heads 93 is fine. At the track you could maybe get 3 gallons mix w/ 5 of 93 and blast it. I was running 93 in my 440-6 w/ 10.7:1 (iron heads) with no problems. That was 36*. I was going to get a few gallons of 110 at the track and bump it to 38*