You can get someone to restore (reflex) the cylinder if it is badly scorched but if not don't worry about it, and also get a new piston and rings. If it is an aluminum cylinder ask someone if it is alright to use a really light sandpaper to get rid of light scorches, if they are present. It is also not a very good idea to use a piston or any parts of that matter in an engine that it is not originally used for. But if you are just desperate in getting the bike just running for now, you can try and see if it will fit, it shouldn't cause no damage as long as it fits properly, though the bike may run differently.