Hemis are more tolerant to detonation than a wedge supposedly. My hemi is 11:1 and runs great on pump 93 (9.50s at 140 mph). Never tried any less octane. It slows down a tenth and about 1.5 mph on 112 race fuel, but it goes a whole lot faster when I turn the nitrous on. 
CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax
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