With the 20cc dish, they are a low compression piston.
They will be 8.94 with a 72cc head or 9.2 with a 69cc head.
That based on either a .027 head gasket, stock deck ht or decking .012, with a .040 head gasket.
Might be good for a low boost blower though, with a stock deck and .053 gasket (8.43).