1982 Mercedes-Benz : 300-Series 300D

Hey all just dropped by to ask a few questions ,I have the chance to buy a 1982 300 turbo deisel for 300 bucks.car is in really great shape for a 1982 .The only problem is it has what i consider a whole lot of miles 270k.I have never owned a deisel or really messed with one before.Just wondering if this was alot?
Also the car has been sitting for about 8 years and now it wont stay running for more than a minute or so.I would say the fuel is junk and would be the first place to start but thats why i am here to ask the knowledgable MB owners. Any info or insight would be appreciated...