I decided to make a sweep of it and decode the raw spool formats for the remaining "Professional" Kodak photo printers, the 8500 and 9810. This means that all of Kodak's professional dyesub printers will be supported, save for the long-since-discontinued ML-500.
But I digress. It turns out the 8500 is essentially a rebadged/tweaked Mitsubishi CP3020D, albeit without 8x12 support and a third variation of the Mitsubishi block-chunked image format -- packed BGR data, sent in one ginormous data block but wrapped in the "traditional' 3020D control blocks. That will require no changes to gutenprint to support, so I'll probably implement support for the 8500 before the CP3020D/DA models it's based on.
Meanwhile, The 9810 is very different from the other Kodak models. It uses a command-stream type of format that's on the verbose side but is otherwise well-structured, with the raw RGB data being sent in a plane-interleaved fashion. Supporting it will require no core changes either.
so, this is my plan of attack over the next couple of days:
Anyway. Time to go to bed.