I will focus my 1876 Plains War main battle on the Battle of the Rosebud as history and with some of its what-ifs over the Bighorn site. Better balance of forces for the army and greater variety and quantity of native allies (that prevented what could have been the first of two annihilations). Actually just ordered some additional figures for my infantry towards that goal, both on foot and mounted (not from Peter Pig though).
Big Horn is just too one sided despite it being the 'famous' battle.
The big challenge - including my Buffalo soldier cavalry! I guess those will get reserved for the Apache Wars though the Buffalo soldiers did make late appearances in the Sioux wars.
As to actual buffalo? 120 painted and based, just need to texture the bases - and, yes, Peter Pig is well represented in the collection as is, I think, some of all the 15 mm buffalo available - adds variety.