There is no "really nice shape" in NRA ratings or Blue Book percentages, there is no way to know what he has until you see it.
Will you know what you are looking at?
A 1912 Colt in truly excellent condition with ALL original parts and a lot of original finish is a collector's dream worth some thousands of bucks.
If the Army ran it through Augusta Arsenal and put on some A1 parts and a nice coat of Parkerizing, it is worth several hundred dollars, maybe a thousand if a pristine rework.
If Bubba made it look real nice after he got it surplus, a few hundred dollars.
If Grandpa got nervous about the FBI tracking down his stolen government property and filed off the serial number, 5 years or $10,000.