I say yes on the upgrade. I think it was quite undergraded, and is a premium gem. The chatter on the reverse is die deterioration, and it should not be penalized for the die state, as they aren’t contact marks, per se.
Pretty much everyone nailed this one, but these two are the only two who nailed the grade and the 6FS. Congrats guys. This GTG is a very good example of "buy the coin, not the holder" because very few people would ever try to upgrade an SEGS coin into NGC plastic.