First 19-3 was shipped in 1967, so that's 50 years. I've had a couple of firearms including one S&W refinished and don't consider that I wasted my time, money, or effort. Could have spent the money on whiskey and women and wasted the rest. It's your son's gun. Sounds like he is already having the gun re-blued. As others have noted, unless he got the revolver for free, he may end up with more invested than he would spend on a comparable gun in good condition. But in answer to your question, refinishing the grips won't change the value if they are in similar condtion to the rest of the gun.