Sunlight should eventually blend the newly exposed gelcoat areas into the old . . . or you could do what I did.
After being on each side of the canoe stern for 18 years, I removed the painted on, former owner's hailing port with Easy-Off. I then lightly burnished the area with a fine, fiberglass rubbing compound, wiped on acetone, applied the new vinyl letters and finished with a good quality wax & polish. The area looks like it was just released from the mold.
True Blue . . .
sold the Nauticat