I don't know of any published games that are specifically Wild West, using the FATE engine.
However, if you want to know how FATE handles action, there's Spirit of the Century (which is pulp action) and Atomic Robo (which gets its action by way of comic books).
Neither of these have massive changes from the core to handle action, mind you. They handle it largely by having appropriate Skills and Stunts available in the game, and then let the core mechanic handle it all.