It's absolutely worth a shot to get it going. There's a manual for the first generation machines posted on this site and it has a blow-up drawing of the Baker/Hill transmission. If you need any help with it there are a few of us on the site that still tinker with the old transmissions. Good luck with the old machine; post some pictures.
Stuck in the seventies- not in the swamp.
(6) Attex, a Hustler, a Super Swamp Fox, (2) Tricarts, (3) Tri-sports, a Sno-co trike, 3 Dunecycles, and a Starcraft! ...so far