Here's another possibilty ...
... that I just ran across while looking for some information on another Western Montana river - this one is the North Fork of the Flathead. Follow the link for some basic information.
http://www.fs.fed.us/r1/flathead/fis...head_river.htm
Access and shuttle considerations for this float are most certainly much easier than for the Selway. I doubt the fishing is as good, although if you hit it just right it could be a lot of fun.
If nothing else, you are right on the western edge of Glacier National Park. Some absolutely spectacular scenery, and if you fish from the eastern side of the river ( which is within the GNP boundary ), you don't need a license to fish.
John
The fish are always right.