Ron,
Love the details and the great pictures as always, and appreciate all the work it takes to produce such quality. Glad to see the body of knowledge about the great and mighty 458WM and cast bullets grow. Of all the myths perpetuated towards the 458WM, none was greater than "it's not a good cast bullet cartridge." Not true of course. All Cast shooting contains a fair bit of Magic to make things work, just go read the BPCR guys process and trials to get through a match and season of shooting.
Hunting with a 458WM and Cast in my opinion is a breeze to accomplish. First of all, we don't need 0.3 MOA to kill a whitetail or anything else. A nice round group of one's loads that land in the same place in a sized equal to or smaller than the kill zone at the distance you want to shoot is all we need. Just like all shooting, one's group at 50 or 100 does not run linear as distance continues. Question is; "does my rifle and load produce a first and second shot ability to land in the kill zone at the range I want to shoot?" If yes is the answer then we are good to go. Mr. Sharpsguy was an exceptional shooter first and foremost and his equipment was built and tested to maximize his God given talent. His results were first the result of his talent and then his equipment.
Your notes above on Cast bullets is a good guide for anyone and any 458WM. I would add, "use a good flat meplat" on hunting loads to reduce or eliminate tumbling and increase penetration and get after them. From 405 grains on up as far as your barrel will stabilize in both air and game is all you have to worry about. A good BIG flat Meplat does a lot to help both causes.
Best regards sir,
Fury01