So I've been wondering something since I actually did it... Not so much what I should do but how people like you might feel about it.
I picked up a copy of Chrono Trigger about 15 years ago from a video store for a cool $10, along with a copy of BoF II for the same price. Good times. Well at some point my copy of Chrono Trigger was lost to my at the time girlfriend's moving boxes never to be seen again until I recently got in contact with her brother who just so happened to have it. He happily gave it back to me but it looked like it had spent that last decade and a half buried under a shed. Cart was stained and dirty, labels were peeling and ruined and I think the fungus living on the copper contacts had become sentient. I was able to Brasso the hell out of the the contacts and get the game working like new.
TL;DR - I bought a copy of some hockey game in perfect condition (because it was never played), blowdried off the label and replaced it with a reproduction label. It looks brand new, and it makes me happy. I still keep the original crappy cart simply because it's the "original".
If the day were ever to come where I were to sell my collection, I'd include that old shell and note that the game had been refurbished but still contains the original board.
What would you guys think about finding something like that and what would it do for your perception of its value?