The big question in my mind is the derailleur hanger - is it original Simplex? If so, it'd be a shame to file it down, which you'd have to do to fit the SunTour. In that case I'd find an all-metal Simplex, and a spare. I have a SX410GT that I don't need. It's almost entirely steel. I'm missing the tabbed washer, but PM me if you're interested.