12.5 to 1 What octane do you run!!!

Now that i have the right carb on, plugs reading much better, and have 38* total timing in it.
HOW MUCH OCTANE DO I NEED? I realize it depend on a lot of things Here is what i have. Rhs heads with pistons at "0" deck, quench is .038" compression ratio is 12.68:1 Live and race at 6600' with adj alt. between 8500- to 10,000' Curent Race fuel is 112.......................... Motor seams to want more timing then 38....but thinking i my want to lower octane instead of raising timing. 112 octane, is all i have right now. Will have to buy my own drum for next year.