I would go with the .460, but i am looking for a companion arm for my Blackhawks and my Trapper carbine, all in .45 Colt; a heavy hitter that can use the same bullets. I think Lyman's .451 Volunteer (450 gr) would be a fine "heavy" for the cartrige, though it does take up some space.
I am waiting for this to become an "over-the-counter" offering: i think if i were to pay for a custom barrel, it would be tempting to rebarrel my Ruger #3 because it's straight stock better matches my Trapper.
If he is thinking about doing a run, please PM me with price and availability.