Wade,
You are wrong in our assumption. The entire S&EV from Walcott to Saratoga was relaid by UP using UP standard 132 Lb rail. This was done in the late 1970's. The only lighter rail that came off that line was the rail up to Encampment from Saratoga, which was pulled up in 1978-79 after the North Platte River Bridge was washed out.
I remember switching out gons full of scrap rail while working on the Sinclair Local.
As far as switches, as well as full turnouts go, I would recommend a visit to LB Foster's or A&K railroad Material's web sites. Turnouts can be purchased from these suppliers in whatever rail weight they happen to have in stock. They will also construct switch rods the proper length for your particular gauge.
Rick Steele