Suzuki 2 Strokes

Hey guys im new here and looking for some help. I got a 73 tc 125 prospector with a dual range transmission from a teacher and if i get it running he will sign me over the title for $50. Im here looking for some pointers on things to do and not to do with it. Im also looking for a good place to get parts. alot of the sights i go to have discontinued most all of the parts. Im in need of an air filter for it and i cant find one on ebay.

Any information you guys have would help. I plan on racing this in some vintage races this summer with some buddies how also have some nice vintage bikes just for fun.