273/235 Gas/Octane Requirements

If the right cam is chosen and he adjusts the timing correctly, he could probably run whatever is equivalent to 91 over there with 10+ CR. Now I don't know if you mean slightly over 10:1 or closer to 11 or 12 to 1. I can't claim to run pump gas yet but my motor is being built with 10.8:1 to run pump gas with iron W2's. But we had the cam custom ground so my dynamic CR is 8:1. Plan is to back off the timing for pump gas and advance it with race fuel at the track. So if the motor is being rebuilt right now, I'd check into that cam.