Concerns purchasing Vintage System?

I'm looking at purchasing a system from a widow that hasn't been played in 20 years. What should I look for? What should I be worried about? I'm a newby to hi fi of the price range.
Audio Research d250
Audio Research d90
Audio Research sp10
Oracle Delphi
McIntosh MR80
Tandberg 3014
La scala
Magnepan MGIII