Have you tried Bob Cantin, a former owner of the company, and a guy who's got a lot of old parts for them? I'd have to dig up his phone number.
I've got a '72 (?) PPT, actually an EasyRider, with really LOW hours from the condition. It's got the Sachs 340 engine, which I'm in the process of replacing the crank seals on. It's pretty much complete. I've done all the factory mods, according to Bob's directions.
It's a front engine version.
I plan to reassemble it and sell it, but if anyone is interested it can go as is.