If someone "gave" me a firearm as nice as that, i'd pay to have it cleaned, checked and repaired. Then i'd keep it the rest of my life!
I'm thinking you will AT LEAST have to have the parts fit to this gun, "if" you ever find them, and also the gun NEEDS to be checked over by someone who KNOWS this type of gun.
I've had this place do some work for me,
http://www.champlinarms.com/ and their smith, "JJ" can make or fit what ever parts that gun needs... He isn't fast or cheap, but at least he does what he says he will do, and turns out quality work...
DM