Keep in mind that most of my knowledge comes from my om617 engines, and a brief stint with a N/A om606
But I look at that list and it looks like a fairly simple, fast, and cheap to-do list, aside from the rear control arms and subframe bushings, but even then, I've dropped a subframe with hand tools in a junkyard in 10-20 minutes to snag a 2.88 rear diff for $50, with tools and a driveway (or garage) it shouldn't be awful if all goes fairly well.
I rebuilt my entire front suspension with new bushings and all that in an afternoon for around $300 (Lemforder parts)
Vac pump bearings can be swapped out for shielded bearings for $20ish if I recall correctly
Vac lines may be more of a pain on your body/engine combo, but still not a huge expense or time consuming endeavor
AC could be irritating, but perhaps not.
Dash pods are irritating. I cowboy fixed mine by disconnecting the center flap and now I get air out that vent all the time. Works great.
Interior stuff can get pricy and time consuming. As can paint. I need wood trim stuff (Its all warped to poop and I can't figure out a good solution) and I also need paint on the hood, roof, and trunklid, but I'll end up respraying the whole car, hopefully this winter or maybe over a weekend if I can avoid working 80 hours a week all summer.
Trans service isn't bad, Diff fluid is easy and cheap.
EGR delete may be a pain on your engine, but those parts do tend to fall off randomly, real weird.
Maybe I'm just a masochist, but I'd fix it all. or fix enough that you're happy with it.
I guess another important thought is are you doing the work yourself? or having it done at a shop? Because $10k is a massive budget to get all that stuff done IMO, If I had $10k to spend on vehicle stuff I'd do all that stuff on my own car, and then buy 3 more W123s and then my wife would murder me for bringing home more cars
