One other thing to be considered is whether you are portraying a garrison troop or one in the field. Troops, including officers wore about anything they had available for operations in the field. That included elements of civilian clothing, including hats, coats, trowsers (sic for spelling). According to Lt. John Bourke, Gen. Crook's aide-de-camp, on the Big Horn & Yellowston Expedition of 1876, "We looked more like a pack of brigands than a military organization." Everybody saved their "good" uniforms for garrison duty. Gen. Crook didn't even wear a uniform. He had a canvas hunting suit and a pith helmet...no insignia at all. There are photos of Third Cavalry officers and men, wearing 1872 jackets, Civil War sack coats, buckskin jackets. Headgear included kepis, bummer's caps, civilian straw hats purchased at a sutller's store.
Even holsters, belts, etc., were not necessarily issued regulation gear! A lot of CW gear including Pattern 1863 full flap holsters continued to be used until the 1881 Patterns began to be issued, and maybe after that. Some of those had the flaps cut to a rounded 3/4 style. A bunch of 1872 Pattern holsters were issued with a Hoffman swivel, which proved very problematic, dumping pistols with the holsters on the ground! Company commanders had their saddlers modify them. Some company commanders in the Southwest even designed their own open-top holsters and issued them to their troops.
In other words, you just need enough to identify yourself as a trooper or officer to "citizens" (as civilians were called in those days).