Earle, go with what VG says above and you won't go far wrong. VG explains it well, it must also feel comfortable to yourself.
Just as a side thought and just my personal view, I prefer light rifles for hunting. Every ounce added to a rifle at the end of the day after a long tramp feels like an extra pound. I've hunted a lot up in Northern Australia chasing Buffalo, carting the likes such as .404's, .500NE and one of my favorites a scoped .338 WM, they all felt pretty damn heavy at the end of the day, especially the .500 double. Nowaday's I just carry an open sighted .303 Lee Speed up North, and a 6.5x53R Steyr made by W J Jeffery down south on the red deer, because both of them are super light and don't fatigue me as much as the larger bores after a long hike. If I was to make another large bore for myself it would be a .416 Taylor on a standard length action and as light as possible without being silly, and only just because of me having to cart it around so much. My rifles are carried more than shot, although sometimes it just feels like I'm just on an armed bush walk.
So what I'm really trying to say is if you hunt a lot with your .458WM and carry it long distances be aware of how much weight you will have to carry, and you really don't feel the recoil that much when you are actually hyped up and taking a shot on a big critter. If you are shooting on the range a lot then a bit of weight will be your best friend if fitted properly.