I bought my replacement motors from XK Specialties, and they fit like a glove.
They were considerably cheaper than putting a Ferrari repacement in, and they are the same thing.
I wanted a better fan than I had, and since I work for GM, I put some pusher fan blades on that were for a Cadillac SRX. I just had to 'massage' the mounting collar the smallest amount and they slipped right on. When I get pictures, I will post them.
'77 308 GTB