I bet the transmission/clutches are okay if the crankcase had a little oil left in it, because they are seperated. If it were me and I couldnt find a decent bottom end, I would just split the cases, press out the crank, clean up the cases, and install a new crank, seals, and main bearrings. You could even just buy a used crank, and put a new lower rod bearring and rod in it ($100), and you would know it is going to last, rather to buy a used bottom end and know nothing about it. See what you can do, and keep us informed! You didnt go wrong at all with that deal, I would have done the same thing. For that price you can put a little time and extra money in it to get it the way you want it to be. Good luck!
THE 80's RAGE! Currently owns:
81, 85 Yamaha Tri Moto 125
83 Yamaha Tri Moto 200 x2
82,83 Yamaha Tri Moto 175 project
85 Yamaha Tri Z 250
84 Kawasaki Tecate 250
84 Honda ATC 70
85 Honda ATC 350X
84 Honda ATC 250R
(2) 84 Honda ATC 200x
82, 83 Honda ATC 185s
81 ATC 200
Lots of other parts and bikes