Bill have you ever tried 89 octane to see if it will run on it without spark knock? I've read reports from a few other guys that claim they have no problem using 89 octane on iron headed engines with over 10.5 to 1 compression. They had the quench set up good. I assume your Eddy's are closed chambers and pistons at zero deck??
Haney I hole you don't mind me jumping in here and asking Bill a question. I figured it's good info for you also.