Standard bore, 0.030" piston deck height, 64 cc heads, 0.015" steel shim head gasket, Chevy flat-tops equals 10.9:1 static c.r.

This will put the squish at 0.045" and should allow you to operate on premium pump gas with a cam something like this. Call your favorite grinder for a recommendation.
http://www.cranecams.com/?show=brows...tType=camshaft