I would send it out to a quality refinisher and have it reblued. You will never be happy with spot cleaning. Let it have a fresh start with your son so he can be proud of it.
I had to shorten a few of the screws lately. An easy way is to chuck the head up in a cordless drill and spin it while running a file across it. You can shape the tip any way you want like with this method.
I had a gunsmith years ago that smoked cigars. Everything you left there smelled when you got it back. Started leaving guns with no grips to avoid that and damn the gun came back smelling and even after cleaning held some smell. Eventually went away. Never heard of such a thing.
Just use blue loctite sparingly. Some guns just have a problem loosening screws. I have shot many revolvers since 1984 and my 929 is the first that will loosen every screw.
I am looking for a 39-2 I traded off about 25 years ago. The serial # is A447936. If anyone knows where it is I would be very interested in purchasing it. I bought it off a good friend and I am getting a bit sentimental about it.
Thanks,Bill