Advice on buying a 1980 300SD w/110k miles

[94E420]

I have come across a 1980 300SD Turbodiesel with 110,000 actual miles. It is a one owner car. Always garaged, no rust, no accidents, original paint, always maintained at the local Benz dealership. For a car of this age what should I be looking for? Issues? Problems? How much should I be willing to pay for it. I have owned 7 Mercedes and I would rate this one a 9 out of 10. It is truely a one of kind car but I want to make a wise decision. HELP & ADVISE PLEASE!!