On my 75 one of the rear foot peg mount studs was stripped when I got it. I had a metric tap and die set. I used the die that fit closest. Turned out to be 12x1.50. The same size as most Japanese and many American car lug nuts.
You can get lug nuts at most auto parts places as well as most auto salvage yards, often laying on the ground. Just pick up a few in the foriegn car section, I like the chrome acorns, clean out the threads with a tap, polish the chrome up. I even grind the tapered part off so it has a flat end to hold the foot pegs on.
I would do the same with a front peg mount but I don't think it will be 12x1.50. So lug nuts won't work there.
Leo