I didn't know they were that hard to cold blue. I've seen blued
Krag
receivers before, but I never tried it myself (and I wouldn't personally do it unless it was a chrome rifle anyway). I think most of the Bannerman sporters from the 1920s were blued. Some of them look very nice, nice enough to pass for original if you didn't know better. I don't know if they were hot-blued or rust-blued.
According to Hatcher's notebook, Krag receivers were made from Springfield Armory Class C steel, the exact same as the low-number 1903s. The LN 1903 receivers were polished after case hardening and then rust-blued. I don't think Springfield Armory used any nickel steel parts at all before the 1920s. The good news is, that makes it safer to strip plating from.
If the Simple Green doesn't remove the chrome, you could try a dilute solution of Muriatic acid. It will definitely remove chrome if the part is fully degreased. The problem with soaking without any electrical current is that you won't have any control over which part of the surface is being etched. If you let it soak too long, it can start pitting base metal in some areas while other areas may still have intact plating. You will definitely want to plug the bore and fill the chamber with wax. If I had a rifle like this, I would remove the barrel from the receiver and strip them separately with 6 volt current in a very dilute solution.
Please let us know how it turns out!