Whilst looking for other information, I found some interesting if not useful NuBus notes.
Way back, when the Mac 128 was worth upgrading, one of the first accelerator and RAM upgraders was Levco. Levco was acquired by SuperMac, who were then taken over Scientific Micro Systems in March 1987. In August 1987, Levco demonstrated the Translink, a tranputer board for the SE and II. A transputer is a specialised co-processor, popularised by Inmos, which was used for graphics processing (fractals, CGI, pattern recognition).
Scientific Micro Systems span off SuperMac and Levco again as separate companies in early 1988. SuperMac retained the Mac stuff (including the old Levco accelerators for a while) and Levco did transputers. The last reference I can find to Levco is November 1988, when they presented a DMA controller card (SE and II) which could manage an expansion chassis for up to 128 Translink boards. I'm not sure whether the number 128 refers to individual processors or boards with more than one transputer. Whichever way, very powerful and very scary.
Edit five minutes later: In 1989, Levco demonstrated a prototype of Pixar's Photorealistic Renderman application running on a Translink.