My 4.15 crank / .040 over 498 RB has relieved pistons at zero deck, and it will be about 11:1 with 84cc Edelbrocks. It has a Hughes 246/250 duration hydraulic cam (.614 / .610 lift with the 1.6 Harland Sharps)

If you have 80cc heads and your pistons are near the top of the bore, I'd guess you'll be over 11:1 compression, which is about as high as you want to go with 93 octane.