The GAF has available the 1875 Marine Corps Uniform regulations here: http://www.grandarmyofthefrontier.org/uniforms/usmc1875.htm
An 1880's Marine NCO would have worn a uniform not much different than that of those worn during the Civil War; Indigo-blue blouse, sky-blue trousers with red stripe, and a "chasseur"- or kepi-style cap. The USMC also issued blue (dress/winter) or white (summer/field) helmets during the 1880's, until about 1905. After 1892 the field cap changed to more of a "pillbox" style WITH a bill, and later (1905) to a Bell-crowned style. The field ("slouch") hat did not come into use until 1898, creased fore-and-aft like the Army, until the "Montana Peak"/"Mountie-style" came into use in 1912.
In the very late 1880's Marines may have begun wearing a version of the blue wool Army shirt (collarless with white buttons), with the blue trousers , and after 1898, khaki. Rank insignia was NOT authorized on shirts (khaki) until after 1902 or thereabouts. Most photos (very few) I have seen of Marines in the 1880's show them carrying shoulder-slung cartridge boxes. The use of cartridge belts began with the issue of the M1895 Winchester-Lee ("Navy Lee") straight-pull clip-loader, whose belt was of blue webbing with black pebble-grained leather cartridge clip pouches, with blue cloth suspenders. Marines began using the Mills web belts after adoption of the Krag by the USMC during the Span-Am War. Marines also began wearing khaki leggings similar to the Army's, about the time of the S-AW, as well.
I have seen a Span-Am War photo of a group of Marines in Samoa, showing the troops with Lee Navy riles, and the officer wearing what appears to be an Army-style "Schofield" holster and ammo pouch, either black or russet leather, worn on the right hip, butt to the rear. Below is this photo, rather small, but perhaps some details can be seen: