He may convert to E85. The static compression on his engine must be 13 or 14:1 even higher than the he thought based on cranking compression test results of 250-260#. He has a fine engine for running E85 with a few mods to the carb and fuel lines etc to supply more fuel. He could even run pure ethanol but that is harder to get and more $$$. Even the high octane gas mentioned would not do him any good.

I had an old FE390 running 12.5:1 with 230# test compression and it liked 115 octane fuel but it liked 130 octane aviation gas even better. It would not run worth beans on normal 105 octane premium back in the dark ages b4 computers.