Perhaps a shorter barreled version of the 460. You can also shoot 45 LC, 454 out of it. Best thing is to determine what you are going to use it for and what fits you best. You can't really go wrong with a .44.
One interesting thing I was just reading in my American Rifleman is a revolver from Freedom Arms and a cartridge labeled the 500 Wyoming Express. Freedom want to use their existing revolver but the cylinder was getting a bit cramped for the big 500 cartridge so they had to reduce thesize of the rim which caused headspace problems. So what did they do? They put a belt on the case. So I guess we now have the first belted Revolver cartridge. This beast can throw a 400 gr slug out at over 1600 fps. But the author admits, the recoil is brutal.