I don't have a clue what kind of stamp a pre-ban might have, as there'd have been no reason for them to be stamped with any identifying marks, prior to the ban. The new, unmarked mags won't work in NY, because of a design change, post, post-ban.
There should be eleventy-zillion genuine G22 pre-bans available. I doubt if you'd get a dealer to ship you one, but I'd be happy to send 'em to you, if I had any. (You might be in violation for importing the mags, but I wouldn't be in violation for sending them to you.)