I had a '74 years ago, those 14" wheels give it a lot more stability than a CT70 at speeds over 40. Don't know if you're going for originality or if you already have an engine, but if I remember correctly the ST90 engine is kind of the bastard stepchild of small Hondas. The engine bolt pattern is the same as a CL or S90, but different than the CT70 or CT90. I put a CL90 engine in mine, and it really woke it up and made it a lot more fun to ride. (4 speed manual over 3 speed auto)