There is one fact to face with these big guns: Sooner or later, unless you are filthy rich, you will start to reload for them.
In that regard a .458 Winchester is a pretty good deal. Cases are easy to find and can be made up (fireformed) from nearly any 2.5" magnum case like the 7mm Rem, 300 Win, etc..
45 caliber bullets are everywhere, including good cast bullets, and the .458 takes to cast bullets and reduced loads like it was made for them. IN fact, the top velocities attainable in a .458 are well within the best performance range of good cast bullets, saving you LOTS of money.
The .458 also has a reputation for good accuracy, if you can handle the rifle. It can be loaded to 45-70 levels quite easily for practice loads.
My "elephant" rifle is a Winchester M-70 375 H&H, and all of the above comments apply to the great Holland & Holland as well.