Jeff,

The CZ's are big, solid, strong, dependable actions. I have owned a couple and they will feed anything you put in them. I did not like the factory triggers. The one I still have has the Number two upgrade from American Hunting rifles. One of the items Wayne changes is the factory trigger to a nice crisp one and adds a three position safety. The other downside to the CZ is they are heavy. The action is huge and perfect for a 505 Gibbs but really a little large for some rounds. However, you could probably put five 458 rounds down the magazine and close the bolt.

I like the Winchester Model 70s (or my left hand world the Montana Rifle version). People who own the Whitworths love them. Both of these options are readily available. this is an example this is a Whitworth listed on Guns International.

Whitworth

In regards to a Lott or Win Mag, if you find a rifle chambered in either one buy it and be happy. not enough difference between the two to worry about. Given the choice I would take a Lott, however would not even hesitate to buy a Win Mag.

The CZ is going to be heavy in the mountains or hunting moose in the thickets. The Winchester or the Whitworth will definitely be better to carry.

Have your considered a 375 H&H? Many more of potential rifles, lighter, less recoil, shoots a little flatter, etc.