Couple of ways to go. You could change the heads for #60669, 95cc and get a 9.5:1 SCR with the pistons you have. You'd have to come back some on the cam. Or you could change pistons to, for instance, Keith Black #206 hypereutectics that would yield 10.15:1 SCR. You still might want to come back a little on the cam. I'll run a DynoSim for you and see what the motor wants....
http://www.summitracing.com/parts/UEM-KB206-030/
These pistons are manufactured with a taller compression height than the H535CP pistons, so the stack works out like this....
piston 1.772", rod 6.605", stroke radius 1.925", for a stack of 10.302". Cut a '72-up block from 10.320" to 10.304" for a squish of 0.050" with the 0.048" head gasket. The earlier block should not need to be cut at all and would result in a squish of 0.046". This should be ok with a hyper piston as they are fairly tight fitting in the bore and would not have much piston rock on the pin. Fit pistons to bore with 0.002" (two thousandths) to 0.0025" (two and a half thousandths) piston to wall clearance. Gap top ring at 0.029" (twenty-nine thousandths) and second ring at 0.018" (eighteen thousandths).