Well, there's no need for a left side footpeg. If you need to rest your outrigger leg, you can just about park it anywhere convenient. But with an open primary chain external flywheel and hot exhaust, there's really no where convenient.
Right side has two places for your leg. A footpeg in the normal sense, and a brace where you would wedge your knee under. It sounds wickedly dangerous and I'm sure there were a lot of broken right legs in those days because of it. You can see the brace about 1/3 the way up the tank right at the front of the seat. Knee goes under the brace, not over.