sounds absolutely fabulous. i bet this guy will quietly brag to his buddies, "DUDE! look what she got me! The '69 Mets!" I predict that you're about to win some serious brownie points with his crew.
One tiny note of caution though - autographed photos from that long ago are probably a little pricey. Sometimes if guys get a $$$$ gift, they freak out because they equate spending a lot of money with serious serious serious committment. If he seems hesistant, and seems to suggest that "it's just too much" you might want to downplay the expense/difficulty in finding them.
Basically let him think the whole thing was effortless - don't want to freak him out with a too serious gift, plus he'll think that you are just naturally perfect.