It is not difficult to achieve 2100 plus with 500 grainers in 458 Win but if you want more velocity the Lott is the answer.
Bear in mind that if big velocity in 45 cal is all you need for spectacular kills, everyone would be using the 460 Wby.
I just bought my third 458 Win, a Whitworth Express and even though it could very easily be converted to 458 Lott I have no intention of doing so.