To be honest any troop types in peaked cap would do, painted in a light khaki drill, although some pre-revolutionary troops still wore the old blue style uniforms especially in places like the Yucatan. I would check out Foundry's Maxilmilian expedition range and Copplestones chinese from the Back of beyond range would make great Federales, in fact i was looking at getting some for a fictitious central American game but eventually got swayed by other projects.