I have done a fair amount of hunting with a drilling here in the states. [12x12x30-06]
I like a drilling a lot, However when following up a leopard I would prefer a double rifle from 9,3x74R up.

I have seen a couple of Leopard tracking hunts where the client used a shotgun. Here I think a drilling with a scope in QD mounts would be good as a couple of times they saw the leopard at a distance where a rifle shot would have been possible.

I am taking my drilling to Africa on my next Safari, mainly for the smaller cats and birds.
I would not hesitate to shoot a Leopard with the 30-06 bbl and if a follow up is necessary I would put a Brenneke a slug in the SGN bbl.

Or better yet bring up the truck and get my 450 No2.