OK is rebluing a 1930 S&W .38 M&P that only has bluing on the barrel ok or is that a turn your man card in offence?
From what you say, I'd send it into S&W and have them reblue it. At least you can honestly tell any buyer that the gun was factory refinished. There are lots of these guns and they are still being made so unless it was carried by Elliot Ness, IMO, do the gun a favor and have it reblued.There is about 10% of the bluing left and it has no historical significance. Most of the gun is bare metal and some of the bluing has turned yellow.
Andy what a beautiful old Smith your wife has. I cant even see a flaw in it.I have a HiPower (not as old as your S&W) that I am going to have re-finished. I say its your gun, if you want to re-blue it, more power to you. There are plenty of S&W M&Ps floating around. Is the barrel original? It should have a s/n under the ejector rod.
My wife's 1948-ish M&P (also not perfect)