Well you could look at Will Ghormleys web page, excellent work and period correct.
Packin Iron seems to be the leather crafters bible...and they give dates and eras of the rigs.
And if you have a copy of Tombstone, guns and gear, they go into a lot of detail of how they put together the guns knives rigs and tack and if they did not exist at the time of the shootout of the OK, well, then it just wasn't put in the movie.
My personal rigs (except my Duke rigs from EPS) and my Ghormley Jessie rig are all done by RedDog leather, and he makes them to my specs, but also follows the period correct rule...:
check out some of me and Old Tops leather at my web page:
http://sdough.smugmug.comlook in the gallery called: Just For Fun
curley