As to the restoring the white in the lettering:
While it depends on the depth of the stamping and location of the numbers,you might try applying a thin white paint to the numbers and immediately wiping across the area so as to remove the paint from the smooth portion,leaving the thinned paint in the depressions.I have done this on a Weaver and the result after several coats didn't look too shabby.This is a variation on chalking the markings on firearms prior to photographing them.
Best Regards
Gene