Hello, Nice Rig Bill, I have one similar I will also show sometime when i get it out of the safe.
Please correct me if I am wrong, but I do not think that the WWI 1917 holsters should be called "Left-hand" holsters.
Bill has already explained that the "left-hand" 1917-18 dated holsters were used in WWI, and the "right-hand" 1942 dated S&W1917 were holsters issued for use with the pistol in WW2.
If I am not mistaken the regulations of the time called for the pistol to worn on the "Right side" with the "Butt Forward" so theoretically they are all "Right hand" holsters, not intended to used cross-draw from left hip.
I also think all the pre WWI Military revolver holsters are made "backwards" or "Left-handed" to have revolver the butt forward carry style. Of course if you were left handed, it was a plus to begin with.