There is current work being done by both
GAMI (their priism system) and Teledyne Continental to produce FADEC controls for the current stock of 100LL burning aero engines. FADEC will provide variable timing and more precise control of mixture into the engine which will allow it to run on lower octane fuel (such as 96 octane unleaded and other fuels).
Variable timing will increase the detonation margins inside the engine, allowing reduced octane fuels to be safely burned. It should also increase reliability. It should bring aero engine technology into the 90's from its current state, which is stagnant in 50's technology.
Bevan..