dave, at 15.5/1 you wouldnt have anymore of a problem with flame travel, or crossflow at overlap than a 440 cu in race hemi engine with 13.5/1. the added stroke gives you more swept volume, therefore giving more compression.

now with what mike said,, with added static compression you would have more heat being put in the mixture, therefore having a greater chance of detonation or you will have to run a more stable(higher octane) fuel. with more compression you would make more torque all over unless detonation would come into play.

jeff