Look here if you haven't already . If he does not list one you should still call him as he quite often can find stuff not in his stock. Joe also does vintage ammo.
VM, I considered the "wanted to buy" but thought I might get more tips about where I might find one here.
LittleAugieMo, I have been in touch with some members of the Ammo Collectors Association of America and their supposed to be watching for one.
Thank you MelvinWalker, for your effort. I have no idea how a "reverse image search" even works, never even heard of it.
I saw a box of that stuff for sale at the S&W Collectors Association Symposium in June. I did not need it so did not make a note as to which member had it for sale. Sorry, not much help but that stuff is pretty scarce so communicating with collectors is probably a good bet.