OK, then I'd personally stick where you are and not push CR up any more; that was the whole point in having this discussion. Higher RPM's typically keep you away from the worst detonation probabilities, and if you get a decent quench, and with the AL heads, then you'll be in a good spot IMHO. You still need to not be sloppy/lazy with tuning and ignition timing.
FWIW, we have an 8.0-8.1 DCR 340 here with quench and AL heads: "Effective DCR" is at 7.8-7.9, since we average around 1500' elevation. 15 degrees initial and mid 30's total ignition timing. Carb is even leaned out at light loading for better cruise fuel economy. It has not knocked a peep ever. Niiiice torquey engine, for street driving and roaring around on the local mountain roads.
