I doubt they are compatible. The spotmatic uses a rectangular VF window with slots on the left/right, much like the K1000. You slide something down over the VF. The P67 has a round screw-in viewfinder window, where you unscrew it, slip the magnifier in place, and then screw it back in.
You will have to get a right-hand handle custom made, the most common maker of these sells them through the auction site.