I find it interesting that you mentioned the 460 S&W case. I owned a Frank Wesson Long Range barrel in the 45-60 Wesson target cartridge. I got rid of the barrel, but ended up building a new version on one of Steve Earle's repro actions. I had a chamber reamer made for it and when I went looking for brass, realized that the 460 S&W case had the exact same dimensions, but was 1.8" long instead of the 2.0" of the Wesson cartridge. I use the S&W cases with the bullet seated out a little longer and it shoots great. I also live in Michigan and have used this rifle to fit into the lower Michigan deer regulation cartridge options. The barrel is marked 45-60 Wesson, so it reduces the possibilities of someone deciding to shoot full power S&W ammo in it. Just something to consider.
Bruce