It is a badly flaked nickeled M&P from early 1929; nothing transitional, all features are correct. Logo on the correct side (1920 to 1937), barrel shaped ejector rod (since 1927). Unless it has a B on the underbarrel flat next to the serial, the nickel is original; the N was not generally used pre-war and just the absence of the B confirms nickel.
As for value and possible restoration, I agree with what's been said already; no collector value left, so anything you do to it can't ruin anything, but make sure you do what improves the gun in your eyes; you won't ever be able to recoup any money you put into it by increasing its resale value enough.