Let me put it another way. There are people here who know how to tell a repop from an original (for the record I am not one of them, but I have some ideas about what they are looking for). Once a car is known to have a non-original tag (especially if you change anything like tire size) word will get out if the car is on the market and it will be suspect.

I might be inclined to put a tag in that says something like, "Original tag rusty" or something like that.