.460 is probably too long to fit in the Deagle, but their BFR can handle just about anything. I've had a long interest in a .45-70 BFR mainly to shoot the 3 round ball guard load. It would basically be a 2.5 inch .410 buck shell on steroids given the balls are .46" instead of .36" in diameter and they'll be stabilized by rifling.I didnt know they had conversions either.
I was thinking of a SW .460, but now I might lean towards another MR gun.