I would lace it on and see if that holds it with no glue. If you need glue, lace it without glue on and dampen it. You can put a plastic bag over the stock to keep it from getting wet. repeat the wetting process a few dtimes, tightnening the lacing any time it seems loose. That will make the leather conform perfectly to the stock. If you still need to, you can stick a few blobs of contact cement under it afterwords to keep it from moving. If more commonly available "contact cement" doesn't hold well, "Barge Cement" will.