I let my father borrow my '89 745TIC turbo+ M46, 128K mi.
He needed to haul boxes to his storage place and he and my mom wanted to double team with his '90 745TIC 200K mi.

I asked to use his DD '87 744TIC M46 230K mi. He replied "sure, no problem!"
I asked when was the last time the oil was checked in it?
He couldn't remember, so I got a rag and checked the oil only to discover that SOMEONE put mayo in the oil pan! Or...?

His B230FT needs a headgasket. Sigh....

I have done a lot of work on this car over the years to keep her running for him but I've noticed that rust is really starting to consume the car.
I've already done repairs to both rear wheel wells and the pass frt wheel well.

It can still be stopped but with a fair amount of work needed to succeed (It doesn't help that in our are the works dept. are using salt brine on the roads.)

The engine has no piston slap or serious issues although she is due for intake gaskets, etc.

I rebuilt the entire front end about 20k miles ago. I've replaced the fuse panel. Rebuilt the entire fuel and brake systems. Many, many other things as well; too much to list.

She does need a new rear main seal, flywheel grind and clutch.

The engine has NEVER been overheated or abused. Turbo seems good although there is blow by from what I think is the CBV (from my research on the BB.)

The delemma: My father has a lot of sentiment for this car but the necs. repairs are going to cost about $500. He doesn't take care of his cars anymore (he used to) and I quite frankly getting tired of putting fires out. I'm not going to charge him for the work; that's just for the parts to do the HG, RMS, and clutch. Might as well do both at the same time and get it done.

Would I be better off pulling the engine and tranny together an servicing them outside of the car?

Or.... Should I even bother?
Opinions about continuing repairing or (Gasp!) parting out the car?