I couldn't do anything with the staining of the nickel finish, but the rest came out rather well.
Have you considered ultra-fine bead blasting? With a small detail unit it's pretty effective, and mild. I've tested it on some old engraved lockplates, the corrosion is removed with no visible loss of engraving, and no "peening".
Ken
Considered it, briefly. I don't have a bead blaster.
Also the entire action, including internal surfaces are nickel plated and I would not want to have it start peeling.
There are still flaws, such as the dents that were too deep, even when steamed and the stock filed and reshaped. Goal was to give it another 70 years of service, not to make it as it left the factory.
