You're a 'tweener, which is just fine.
They can probably tolerate 12.1 A/F at the launch, but play-around. See what happens as it approaches 12.5 to 12.8 at the hit. If the 60's don't like it, go the other way.
I imagine you run C11. You can normally go up to 13.0 A/F with that fuel without hurting power. Heck, I have seen up to 14.0 A/F and not hurt the engine, but it did slow down. Again, find out what it likes. Some engines like a flat fuel curve from start to finish, others like to change A/F though the pass. With EFI we are free to experiment with just a few keystrokes!
I have found the higher the octane, the leaner it likes. I have not used oxygenated fuels so I can't speak for tuning them.