Thanks
Yes, the rear drums of a 412 are in fact most all type III parts. All, but the rear hub. That unique rear hub is what neccesatated the complicated spacer.
I have long thought it wasn't possible to use 944 parts and not having to weld anything on the arms, but suddenly, on a bright moment, I got the right idea and a friend from a friend was able to make what I had in mind
After that it was a 'bolt-on'.