Well, OK, here's what I would do: (and thank you, Charles Isaac!)
As was done at Hartsuff, split the class between Levers and Milspec. Lever class stays as is (SASS Standard)
Milspec class: Milspec rifles and handguns of the Era of Expansion 1900-1916, items identified with WW1 excluded (No helmets, gas masks, etc.) period loading aids allowed (Stripper clips, bloc clips, chargers for the Krag, half moon clips for revolvers, etc) NO shotgun, shotgun targets engaged with the handgun. (do this at my local match, its a hoot) Shooter has 4 options for dress: cowboy with any weapon, Villista with any weapon, US army with any weapon (In the Movie after all, the US Army outfits were a disguise) Or uniform to match the rifle. Both 1917s (rifle and pistol) and the basic 1911a1 allowed, developments of earlier weapons. NO OTHER EXCEPTIONS!!
THIS IS A SIDEMATCH! Don't even think about asking to use any of this in the main match!