I doubt that being an original sticker. The dealer was supposed to remove the sticker before the car was delivered and most of them just took a razor blade and cut if off. I'm sure that if someone bought a car back then and had foresight enough to want to keep all the paperwork then they would have made an effort to remove the sticker without destroying it but that wasn't usually the case.
I purchased my 61 SS from the original owner and he saved every piece of paper work that the dealer gave him but theit was no winow sticker, he said they destroyed it when they removed it. I considered having one made but then decided against it, I had every original piece of paperwork and an original one owner first year Super Sport, why add anything fake to it.