I calculated with a 67cc head chamber, 5cc valve relief volume, .041" thick x 4.190" bore head gasket, and piston .020" down bore @ TDC and that results in 10.72:1 compression ratio with a rather wide .061" quench clearance at TDC(quench is actual assembly piston-to-head clearance).
With a 73cc head and everything else the same compression ratio drops to 10.09:1
Zero decking the block to tighten quench up to a more optimum level results in 11.25:1 with the 67cc head and 10.55:1 with the 73cc head. Optimum quench is in the .035-.045" range and helps reduce octane sensitivity even as compression ratio is slightly higher. Tight quench improves power also, most effective at part throttle.
Without more guidelines on the rest of your combination, can't recommend a cam....but I can say this, any cam except a hydraulic flat tappet.
The ProMaxx 225cc is a pretty good head for the price.