If you use clean or empty templates and replacement face templates, they will generate with faces from the face template replacement set. Or you could use SimPE's Sims Surgery to replace their appearance.
There are also these Pleasantview replacements that will generate alternate NPCs for you:
http://www.genensims.com/guest/MadameMim/neighbourhoods.htm You don't need the Wild West clothing for the Wild West template to work for you. The NPCs will just generate with default Maxis clothing. Those are the only "default replacements" as such that I know of. Basically, what you would need is a default replacement for the Pleasantview template, which is what Scotia and Wild West are. I don't think you can make default replacements for specific NPCs' faces.
