Looking at an '87 300D Turbo sedan...have read buyer's guide...opinions?

[Zwoobah]

Hi, I'm new to mercedesshop. From what I've read so far, it looks like this place is THE place to be for older Mercedes. While I have no MB or diesel experience, I've been working on older German cars for years...my current stable includes a '95 Audi S6 and a '91 BMW 325iX.
Anyway, I have the opportunity to buy an '87 MB 300D Turbo sedan. It's cabernet over palomino MB tex, same owner since 1991. 263,000 miles, price is $2000.
All power options work inside, except the power headrests. All lights work and are in good condition. All glass is perfect. Interior is in nice shape, although the carpet could use a good shampooing. Exterior is dent and scratch free, although the paint could use a good buffing. The car has been repainted once, and the airbag was replaced at some point in the '90s. There is some mild rust on the rocker panels, especially around the jack points, but the body is otherwise rust-free.
Mechanically, the car recently had several thousand dollars of top-end work done. I assume this was a head rebuild/headgasket job, because the head is still the original (casting #14). It appears to need a serpentine tensioner (it's cocked at about a 2-degree angle). The fan is also the original metal one, although there doesn't seem to be any play in the fan clutch. It runs strong, 10.5 sec 0-60, not much smoke, smooth idle. 1st-2nd shift is a little clunky, feels like it might need a transmission mount. There is a little bit of oil in the coolant reservoir, and it is currently running green coolant of unknown origin. I'm not sure if this oil is left over from the previous blown headgasket, or if it's a current problem - any way to check?
The oil is also very dark black. It appears that the previous owner was pretty meticulous about oil changes - is dark oil characteristic of a diesel? Or does it just need an oil change?
The AC does not work, and the center vent diaphragms are nonfunctional.
It appears to need new front shocks, as the front end sits quite a bit lower than the rear. It rides fine, no unusual noises. The engine didn't get above 90c or so, in 85F ambient temps and hard driving. The radiator appears to be a few years old - it's got an MB part # and has plastic end tanks.
It drives great on the road, no vibrations, and the brakes feel great (master cylinder looks recent). Plenty of life left in the pads and rotors. The tires all have plenty of tread.
What's your opinion? Is this car worth $2000?
I am mechanically inclined, and can handle replacing the small items (belt tensioner, suspension, etc) but have no interest in replacing a cylinder head. This isn't a car I plan to keep forever, but I really like the way it drives and would love to use it daily. Thanks in advance!

[rs899]

Do you feel lucky?

Except for the oil in the coolant, I think it is a decent or better deal. One of the OM603 guys can tell ya better. Black oil is normal condition for any diesel.

[Zwoobah]

Ok, I did some more reading, and went out and checked the upper radiator hose this morning. No pressure in it, which is good - a sign that the head is OK.
The radiator fan seems to run constantly, even when the car is first started and cold. I assume the fan clutch is seized? It is the original metal fan, has not been updated.
What precautions should be taken in a car with a #14 head? Extended cool-down time?