Title 26 says:
5842. Identification of firearms
(a) Identification of firearms other than destructive devices
Each manufacturer and importer and anyone making a firearm shall identify each firearm, other than a destructive device, manufactured, imported, or made by a serial number which may not be readily removed, obliterated, or altered, the name of the manufacturer, importer, or maker, and such other identification as the Secretary may by regulations prescribe.
5861. Prohibited acts
(g) to obliterate, remove, change, or alter the serial number or other identification of a firearm required by this chapter
So, your firearm has the importer's mark per Title 26, chapter 53, paragraph 5842, section a. If you remove it, you will be in violation of Title 26, chapter 53, paragraph 5861, section g. The "other identification" clause seems to cover what you're proposing.
It's also a separate violation to transfer a firearm that's been so modified.
Of course, the surest way to find out would be to send a letter to the BATFE because this is all just my opinion.