The Coeur D'Alene War of 1858 is a potential good one - combined arms operations, infantry, cavalry and howitzers against mounted tribal war bands. The Battle of Four Lakes and the Battle of Spokane Plains (or elements of them) might make cool scenarios depending on the rules you're using, although in reality the Indians were outgunned due to new army rifles outranging the old trade muskets the Indians were armed with, so the scenarios would need careful consideration.
I'm personally planning on using Perry Civil War Union figures (with some head swaps - campaign hat instead of kepi on some models) for some gaming set in that campaign and the wars of the 1860s - the Minnesota War and the Apache campaigns around Apache Pass, plus Red Cloud's war, the campaigns against the plains tribes in 1864/65, etc. I know the civil war look isn't quite right for the 1858 campaigns, but they'll do...
I've already converted/preppped some mounted and dismounted cavalry, but the project is in a queue behind some Back of Beyond/WW1 stuff at the moment. Having said that, I might paint a few cavalry soon just to give me a break from the mass of khaki I'm painting currently

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