We did alot of swapping back then with the oe parts. if your two donor rigs have the same bore as your onhand parts I would use them if they fit the ring grooves and give a ring gap from about .012" out to .018". Lots of times in the life of something it will get some other piston made by another company, wiseco being really common and stock rings may not fit, and probably wont fit in wiseco's case. if you get the ring gap you want, and they fit the slot and have a similar profile on the pins I would use them up. fyi yamaha used that bore on lots of their 350 twins including some for the roadracers. you could get some pretty wild running 175's by simply using the road race piston and port timing.