Nice little review, you may pick up a few of the old Deadlands miniatures which are also on the large size more akin to black Sorpion.
Foundry have 2 ranges the original Perry ones whihc are lovely but quite small and the later ones typically a few gunfighters and the Border raiders, mountain men etc which although they fit in well are larger and more akin to Artizan minis.
Add to this perhaps the Brigade wild west which are by Paul Hicks and work nicely with Foundry and Artizan. I havent seen others such as the Old Glory/westwind ones or knuckle duster ones so cant comment.
Dixon have a range but a lot are quite old though some nice. SHQ have the old kennington range and you can find a few odds and sods amongst those too.