I have a large stockpile of collets, seats and so fourth, even the most dud engine can relinquish good parts - most extreme example was an engine I bought on which all the lower cases had corroded past use and internally full of mud - gearbox was full of rust and eventually I knocked the bottom end appart with a hammer as the selector forks and drum were fused solid, the head was however prestine under all the oily sludgy mud that it was full of.