The 85 380SE has a double row chain, unfortunately it reached it's limit before it was changed. The value of the car is personal, if it were mine, I would search for a good used engine and replace.
Try these guys:
http://www.mercedespartsused.com/
or
http://www.silverstarrecycling.com/
Both of these guys are in California where I get my parts from when needed.
Good Luck!

__________________
Doug
'83 300SD "Old Gold" 170,000 mi.
'82 380SL "Green Machine" 190,000 mi.

Some days you're the pigeon, some days you're the statue... I'd rather be the pigeon!