The solution really is to buy a .375 H&H. It does everything you’re wanting to do, better. Shoot the two side by side on moose and bears, and you’ll see a trend over the seasons in favour of the faster .375. I have more reverence for the .458 Lott, however few including myself enjoy the recoil.
.458s aren’t without merit, they smash heavy bone and penetrate six feet when needed. Problem is that’s a rare calling on this continent, of thin skinned game that react more to a modicum of speed than bullet weight. It’s becoming a rarer and rarer calling anywhere frankly, as we destroy the last great wildernesses.
That’s the .458’s allure, it’s a monster rifle, without truly monster recoil. That captivates the imagination, even if a .30-06, .300, .338, or .375 will serve better for what we want to do here.