Any Uno FIRE engined starter motor will fit, so you should find some in scrappies. I'm not sure but the Cinq FIRE's might also fit as well? I have a spare Uno starter but I'm holding on to it just in case!
It's for the 903cc ohv engine so might not fit. I know the 1116/ 1301/ 1372cc engined Unos use a different starter motor to the FIRE, so assume the 903 would also be different. The problem is the bellhousing and the location as the 903cc engine has the starter at the front of the engine whereas the FIRE has it at the back.