Buford,
The 458 is a standard length action the lott is a magnum length. 2.5 vs 2.8 inches. You would need a magnum length action to acomplish this some thing in .375 or .416, I don't think your action or your magazine box are long enough.
I am not 100% sure on this however. Check with a gun smith. Your .458 may just be long enough the manufacturers sometimes use longer than neccesary actions.