Picked up a M1907 sling off eBay from seller that claims it was unissued. It certainly was not issued, but I don't know enough about these slings to know whether it's legit.

Arrived behaving like stiff cardboard, so have been "marinating" with leather conditioner to restore as much flexibility as possible. Making substantial progress, but still too stiff to attach to my Enfield No. 4 Mk. I (T) (yup, the Brits issued their WW II sniper rifles with American slings, presumably cannibalized from the massive number of P14s received via Lend-Lease).

Short strap is dyed dark brown on both sides and clearly unissued. No (or extremely minimal) leather cracking or splits. It's embossed (stamped) G&K, 1918, JLR on the exterior just below the brass hook.

Long strap is dyed dark brown ONLY on the exterior while the reverse is undyed standard light brown leather. Again, clearly unissued. No (or extremely minimal) leather cracking or splits.

Do I have a real 1918 M1907? Hope the photos show enough detail.

Should I dye the long strap reverse the same dark brown as the exterior? If so, what leather dye should I use?

TIA.