I can't help you with what nut to use, but that one on 1977 is left hand thread so it should work. On my 50v the Novi nut is F'ed a little. I used a 3/8 ratchet shoved in there, sprayed WD-40 on the outside edge. Then put force on the ratchet and tappd the edge of the nut with a hammer and it came right off. Mind you it was sitting out for atleast a year in the Florida season of rain and heat.
That's the same puller I got from Nick at the Inverness ride. Works on the variator and fly wheel.