Joe,
I think it was just a difference in the masking of the emblem when it was sprayed black. The chrome is intact under a very thin coat of black on the sides of the "SS" characters, you can likely scrape the paint off and polish the chrome on the NOS and produce a usable part. If your original is not pitted, you can always recondition it - masking might be tougher than brush painting (my hands are probably not steady enough anymore to brush it on). I might try the paint removal rather than paint addition when I replace mine. The NOS piece I just received looks identical to your NOS pic -
Regards,
Steve