Vince,
The most important part of a KU is the vintage/story/background information. Try to get as much of it as you can.
Questions to ask:
-Where did it come from (deh, Germany. But whereabouts

).
-Where was the father stationed.
-How did he get it.
-Does it has capture papers.
That information is invaluable and far exceeds the value of the pistol.