Joseph, Jaems,
I had to dig in my memory - Google helps a bad memory - and yes, it seems they are still available. Zims Autotechnik sells a conversion kit:
356 or 912 Alternator Conversion Kit
It is - add the money for the alternator - more than three times the money for an original 912 Bosch generator, but it includes the stand and all the other parts you need. Almost a piece of art. And if you want to return to the original generator, it's reversable.
Otto