Yeh, R.h = off with magnito, L/h = off with clutch basket& primary gear, Screw two self tapping screws into old seal, and pull out,
When intalling new seal" a litttle lube on edge, as its a tight fit, be gentle with tap in with big socket ,, dont bash bash, as seal might get damaged, , As for Main jet size, 150 was standard, upping a size is a fine safety measure when on full throttle,