The best thing to do with electric pencil marks is to just get used to them, maybe swab on some cold blue to cover the shine.
The reason is that an electric pencil of the normal impact type actually pounds the metal down where it hits. So the metal is not just cut into, as it would be with a graver, but is compressed. You can polish it down until it looks good, then when you blue it, the marking shows right through. By the time you get down to undisturbed metal, you have a very visible "gouge" in the area that looks worse than the original mark.
I don't know if the gun was re-blued or not, but if it hasn't been, any tank type reblue will look wrong on that gun, plus the polishing that will be given it by most gunsmiths will make it shiny.
I would leave it alone; it is what it is, and it bears the marks of its history.