You can. But you have to make your new polish match what the original polish was under the engraving.
Coarse new polishing lines bracketing an old marking or area of engraving are a giveaway of that technique when not done right.
Plus you have to figure in what the new polished surfacse will look like after your rust bluing (any matting effect). They have to again match what is under those untouched areas of engraving and markings.
Otherwise the engraved area will show as different. Sometimes not by much,,sometimes a lot.
The old surface no matter how pristine it may appear is usually loaded with tiny marks from handling. They don't show until side by side with a really pristine new surface.
It's something that is done in restoration work quite often so it's not anything that unusual. But it takes some skill to really make it look just right in most instances.
If just rust bluing over an old previous rust blue,,it really helps to break the surface of that old blue with a light polishing with something like 400 or even a scotchbrite pad.
You are not even trying to remove all of the old blue, just cut the surface of that old finish, removing any old dried oil usually in the pores of the matted finish and bringing a clean surface for your bluing to eat in to.
You shouldn't have to scuff the old color much beyond a light blue grey if the finish is still pretty good.
The really thin color/finish spots will catch up in color after a couple coats and any new polished areas from dent removal, ect there after.
Saves a lot of extra polishing sometimes.
The key is matching the underlying polish so everything looks the same when done..
