Best way to reduce compression ratio?
x2
I'd start with a re-jet on an O2 readout and ignition timing a li'l.
If nothing else, richen up the mix and throw a lower thermostat in it, if not some coolant additive as well.
E-30 up to E-95 all have issues with availability and require coated float bowls, gas tanks and replacing rubber seals with synthetic ones to run on a regular basis. It works, but I think it would cause the same issue with not finding 93. supply/ demand issue.
The easiest fix would be premixing fuel with 100+ octane rated, but that can be a hassle for some uses.
