I think you should try to find something unusual. Most of the western names, have been done to death. By the way, is he registered with any organization? If so, his registered name might be quite different, from his call name.
How about " Uncle Buck " , I think that was a movie with John Candy, comedian. Or Buckshot, Buckaroo, May Buck, or if you're old enough and have this sense of humor Buck- you . He'd still hear a name he's familar with but it shakes it up some. I had a QH years ago named Bay Line Buck, one of the best, maybe the best horse I've ever owned. Have fun naming him, he looks great!