I've been interested in gaming the 1885 Riel Rebellion for quite some time but have never managed to get a project off the ground - best wishes and keep us posted!
Although the campaign was quite brief, all over in a few months, there were a number of interesting battles, including a couple where the métis and/or the Cree got the upper hand. The Battle of Fish Creek in particular would do well with a system like Sharp Practice, where the Cree could use hidden movement (i.e., blinds!) to mask both their numbers and positions. There's even an opportunity to use armed paddlewheelers!
As mentioned, Rafm has a dedicated line of 25 mm figures. These are tiny compared to modern 28mm figures and not as nice as newer offerings, but they are pretty accurate for the conflict. If you are set on 28mm, note that the Perry BIF are focused on 1860-1865, with the potential to stretch to 1870: using them for 1885 is a bit of a stretch. For example, the Kilmarnock caps are well out of date by 1885. Glengarry caps seem to have been the most popular headdress from what I've seen.
You'd think that Zulu War British would be a good match except that the Canadian Militia were still armed with Snider Enfields, which look nothing like the Martini-Henry rifles of the Zulu War.
Anyway, best wishes and keep us posted!