I have an old book called "Souping the Stock Engine" from about 1940 I think. They discuss all sorts of stuff like the new fangled OHV engines and even OHC aftermarket heads. They also get into mixing fuels and even adding mothballs and the different fuel properties.
My little 100cc bucket racer has 15.2:1 compression (measured, a couple of times) and I use nothing but 100 octane from Kumeu BP. So far no problems even at Pukekohe. Have had no problems with inconsistancy either.
You really need to try these things on the dyno. The old seat of the pants can tell untruths.