Another progress report. Sorry, I don't have any photos:
* Recapped the analog board and PSU board (again, thanks to
@JDW for his video on the latter, particularly with how to deal with the extensive use of hot glue). I used the Console5 kits to do the recapping.
* Swapped out the exhaust fan with a Noctua fan
* Refurbished the floppy drive, cleaning it up (the front was clogged with dustbunnies), and lubricating all of the essential bits with lithium grease (and giving the upper plate part a spray with PTFE dry lubricant). I replaced the Gear That Always Breaks in the eject motor, and relubricated that whole part as well. I tested it on my IIgs to see if it could handle the basic operations (read a floppy, write to a floppy, and ejecting the floppy), all good.
* The floppy drive cage was a bit rusty, so off into the rust remover it went
I did an assembly of the boards and PSU and monitor to see if it would boot and.. no. No chime and the screen was a mess of vertical lines. Likely one of my ROMs is bad (I can't remember which one, but it's the one that I didn't solder very well). But no magic smoke escaped, so I'll take that as a win.
The main next thing to do is to soldered the newly programmed ROM PLCC chip onto the adapter board, which will be whenever I have a nice block of time to patiently deal with that.
Dealing with rust is less urgent given that I live in a fairly dry climate, but the floppy drive does have some of its metal bits that have rust on them. I'm tempted to just leave them be at this point, vs potentially damaging something by getting a dremel or wire brush touching something that it really shouldn't, or getting sanding residue into the mechanical bits. I haven't painted the frame, but that is sheer avoidance of doing the hard work of prepping the frame with some sanding / steel wool.
Edit: to add a quick shoutout to
@max1zzz for his Mac SE PLCC ROM board whose files I used to order the SE ROM boards, and if I keep soldering them as poorly as I have been, I probably will need to get more.