"I will do my best to shoot lots of North American big game with it, but am not sure I will ever end up in Africa. Something about dropping huge cartridges in the chamber and closing the vault is just awesome"

A .470 or .500 N might be too big for the majority of North American big game.

Perhaps you may want to consider something smaller, for example a .375 H&H magnum as an all rounder. You can shoot every animal on earth with a .375 without ever being over- and only rarely undergunned.