I have a contact at a major piston manufacturer who will make custom pistons, good news as they will accept VERY low minimum orders and incorporate improvements(like single ring, moving ring pegs etc)or just make a copy of the original. Prices are very reasonable also.So if your bike(s) are running out of pistons and can supply a sample or a drawing and have between 4 and 10 like minded individuals, the run can be done easily.
Contact me if you want more info etc etc
Cheers