The hands down "logical" choice is .458 Lott (3.600", .532") due to ammo availability.
.460 Wby (3.750", .579")is the next step up, but still has ammo available.
.505 Gibbs - (long cartridge - 3.850", .640"), .500 Jeffrey (3.465, but varied specs, .575"), .495 A-Square (3.600", .579"), .500...