I'm sure that Perry do dismounted cavalry to match these but only in metal... Perry figs are always worth a look and aren't too pricey when you consider the sculpt quality.
As for the suitability of the figures, I agree with everything that's been said above - ideal for the early plains wars (1862 - 1870 ish) so, Red Cloud's War, various campaigns against the Cheyenne (e.g. the war involving Roman Nose and Beecher Island), Custer on the Washita, the wars against the Kiowa in 1868-70 (I think), etc....