If you need to reblue/repaint the protector, I think it makes more sense to go back to the idea of replacing it. Unless you are dealing with an early "waisted" protector (narrower in the middle than the top or bottom, similar to a Pattern 1914) you should be able to find another with exactly the same markings and matching condition with a little searching around. If the protector had been bent in the field during wartime the local level armourer would have done the same thing - without worrying about what markings might be on the replacement.