I browsed internet concerning unleaded AVGAS and it looks like 100 octane is just starting to come to market. The octane tests are different for AVGAS and MOGAS. One source said 100 octane AVGAS is about 105 R+M/2 rating. R+M/2 is what is displayed at the pump.

Maybe convert to E85? It's about 105 octane.

10% toluene will increase octane about 1.5 numbers. Toluene is already in gasoline. MEK is methyl ethyl ketone. MEK is not found in retail gasoline. It is a strong solvent similar to lacquer thinner. So I'd have some concerns with MEK as an octane booster.