(Subtitle: "Hey Ted, that was kind of brilliant")
So, this happened tonight:
Thanks to a cheapy body cap, some short work with power tools (ooh, power tools) and an old set of macro-photography bellows that I inherited, I bring you operation "Great googly moogly, this might actually work." The bellows adjust for the long focal length of the lens perfectly.
The lens is just resting inside the hollowed-out cap at the moment, since the threaded ring that held it to the board was too large to fit inside the new mount. I'm going to look at options for this -- maybe a rubber ring to friction-fit it into place, with some tape to be extra sure? I don't want this to be a permanent attachment. And I need to get into the shutter mechanism again to figure out how to get the "T" setting working again so it doesn't require four hands to operate.
Dang. I've almost finished something I started. I may have to walk away for a year or two just to pace myself.