JPK
Have you thought about scoping your 458 double?

Say, maybe with 2 scopes fitted in claw mounts.

One a S&B 1.1-4 with illuminated flashdot reticle sighted in with the 450/500gr for buff when necessary, and lion, [like you I prefer iron sights for elephant].

And two, a S&B 1.5-6x42 with flash dot reticle, sighted in for North Fork 350gr Soft [the only soft he makes that HE considers safe in double rifles], for leopard, black bear etc.

That would make your great 458 the perfect 458 double.