Just purchased in great condition an old Miss Buzz Western Flyer. actually the chain guard says B.F. Goodrich Super Fireball but its a Mini Buzz wit the step thru frame. Has 20" wheels and motor kits say there for 24" and up. I do see an issue with not having enough clearance for a 415 chain to pass thru the rear wheel frame. I would like to use a chin tentioner from turbobuick. Thinking I could fabricate a curved tube and cut and weld it in where the chain would pass thru to give the chain enough room. Are there any other issues that could arise using 20" bike?