I bought an '88 420SEL, which was a grandparents' car with 75,000 miles and totally refurbished it; see:
http://www.peachparts.com/shopforum/showthread.php?threadid=28337
This (along with the other suggestions above) is just about everything one would need to do -- the frontend investment gives a solid road car that should, with continued regular service, provide dependable service for some time -- and they're not nuilding them like battleships anymore!