In this part of the globe, we have either 95 or 98 octane fuel to choose from, I'm running 95 with lead additive and factory timing (9 btdc), engine is completely stock with exception for a 068 cam. Never had any problems w knocking, however occasionally I'm experience some diesling when shutting engine down after running on the hotter side for a while. Might try the 98 octane and watch if it makes a difference. Or even some E85...