Firstsks, congratulations, your father has fine taste. Fox shotguns are regarded as being among the best American made firearms. Many books have been written about Ansley and his guns. There are several types of Fox:
Types of Fox shotguns:
1) A. H. Fox guns from Philadelphia.
2) A. H. Fox guns from Savage, built in Utica.
3) Fox Model "B" shotgun built by Savage on a Stevens 311 design - related to the first two by name only. This one is the "poor cousin".
Which one do you have?
Within the first two categories (Philly & Utica), there are several grades - The Sterlingworth is the lowest grade, followed by grades A, B(rare), C, X, and F. There are some other configurations as well. A graded Fox (A and above) will have its grade stamped on the water table next to the serial number. The barrels will tell you if it is a Philly or Utica gun. With the serial number in hand, you can go to this web page and determine the age of the gun. (scroll down a bit)
http://gunshop.com/dgsnos1.htm
Except for the earliest Philly Foxes, a gun in sound shape is good for modern non-magnum ammo (check the chamber length). Foxes were advertised with the slogan "The finest gun in the world". While that might not be true, they certainly are fine shotguns. They are still made today, starting at $10,000 U.S. An early graded Philadelphia gun in top shape will fetch many thousands. Stirlingworths are usually in worse shape than the graded guns, but still command prices around $750, more if in top condition.
I would take the gun and keep it forever, no matter which model it is. Shoot it in good health.
Sharptail