The horn looks all original to me. The heavy scuffs on the plug appear to be some kind of heavy modern abrasion. A lot of the Newfoundland horns, and/or eastern Canadian seaboard horns, appear to be a little more heavily, or deeply, cut than better American horns, making the lettering, while a little crude at times, stand out sharply from the background. While not the best carving, at least those horns will be readable for a long, long time despite their past, and future, handling and wear.
Shelby Gallien