MY340, what exactly are you referring to when you say "reworked" heads...as in a good valve job or something? as far as compression, how far up could i go to still run on 91 octane...perhaps 9.5 or 10:1?
Offten "Re-worked heads" refur to a rebuilding of the heads with minor performance mods done to it. Things like a milled deck for compresion, trick valve job and/or new valves along with it is the basic idea.
While basicly a stock rebuild, the added "Tricks" allow for nice gain in performance with still what is basicly considered a stock head. No porting done at all.
IF 91 octane is your best gas at the pump, I would stay at 9.5-1 as a absoulte max. If your running a small cam, back it down a 1/2 point of compresion.
