Tom., With this era are a lot of modern uniform plates, illustrations, "reenactor art", movies, reenactors etc, plus modern imagination by the artist as to what these men wore on campaign. There was issue gear and reports of civilian dress used for utility and because of supply shortages. Some of these are documented such as the civilian straw hats sold to Custer's men just before the LBH battle. You have to guess what brand and what style these hats were. These straw hats show up on reenactors and in the movie Son Of The Morning Star but they are the off the rack "Amish" hats. Color shades used in illustrations vary.
Perhaps old Civil war gear was used up until the early 1870s gear and clothing was issued. Here's examples of repro CW clothing war clothing.....
http://www.quartermastershop.com/CW US Enlisted/us_enl_uniforms.html
Here's repro Indian war clothing.
http://www.quartermastershop.com/1872_and_on_us_enlisted/indian_war_enlisted_uniforms.html
You can go too far wrong if you paint your figures with examples predating the event portrayed . TSSD figures are late 60s. Paragon are 80s.