Do as i did with mine, i had the same problem a pair of years before due a defective sproket that ate my driveshaft at 7500 rpm, i just changed it with one of a gs450, the same measurements, cheaper and safer cause it have a nut replacing the circlip, this avoid any kind of movement.
Since the change i`made more than 25.000 km and changed sprocket with no even visible scratch in the driveshaft.