'87 560 Sel

I just looked at an '87 560 SEL that was advertised on Ebay. Click the link to see the ad:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&category=6332&item=2449009160

I actually didn't win the bid, but I contacted the guy who did and asked him if he was interested in selling.

He said yes and, coincidentally, was driving out to L.A. with the car. I just looked at it and found it to be impressive, but there are some fairly big things that are wrong with it.

-Aux. Fan does not come on with A/C compressor clutch.
-Center vent on dash does not deliver any air, only side vents and rear passenger vents operate.
-There is a slight tapping sound (like a lifter) on the passenger side that comes and goes
-Two of the front plastic lenses are cracked (side marker and fog lamp)
-Tranny takes up to 3 full seconds to shift into reverse
-Some curb damage on wheels
-left rear window does not work with door switch, only console switch
-Climate control wheel is in Celsius
-Rear seat recline inoperative
-No CD player
-#1 preset button on radio missing
-Oil pressure indicator twitches (stays at BAR 2.5 at idle)

Some good things I noticed were:
-Engine runs very smooth at idle and all the way up to redline
-Tranny seems to shift smoothly and at the proper shift points.
-Braking is very smooth and straight
-Rubber around windows and door sills looks like new
-All leather, including driver's side is a 9 out of 10 with very little wear at all
-Driver's side seat springs feel new and firm
-No body damage
-Engine bay is clean and free of leaks, yet doesn't look freshly pressure-washed.
-Drives nice and feels balanced and happy at 90mph.

As you can see from the ebay ad, the previous owner did sink an awful lot of money into the car. I love Mercedes and don't mind buying the repair CD and digging into the knick nacks that are wrong. Fixing little stuff is sort of like a hobby for me.

-Is the aux fan supposed to come on with the A/C compressor clutch? The OAT was about 50 deg. at the time.
-Is it okay that the tranny takes almost 3 seconds to engage into R? I've read some previous posts, but couldn't find a definitive answer on what this probably means.
-Why is the climate control wheel in degrees Celsius? Does this mean that the car is a Euro-Spec model?

I feel comfortable fixing all of the little stuff, but would love to hear input from anyone who has it. The car shows the following values:

Kelley Blue Book
$3650 trade-in
$5300 private-party

NADA
$7425 low retail
$9075 average retail
$10225 high retail

I think the guy who just bought it has a little bit of buyer's remorse. He said he'd take any offers. I told him that if I could get it inspected and could get assurance that the evaporator was okay, I would be willing to give him $5800 for it.

Please tell me if I should walk away, or if this could possibly be a decent deal. Thanks in advance for your time in responding.

-Josh