Unfortunately this is the only reproduction of the WWI leather sporrans that I am aware of. I have nudged USAKilts to get a proper reenactor line set up, will have to be more blatant.
The only stampings are on the inside of the flap: W.P.G. Montreal 1915. Nothing relating to the 42nd.
I will have to dismount, swap and trim the tassels to get the 100% correct look. Weirdly, it looks just like the picture in their website. So either I have the one they actually photographed, or they are all made with strangely incorrect tassels.