I generally consider that my scope choice and my cartridge choice should be dependent upon my desired targets and desired ranges, but not necessarily interdependent upon eachother.

In other words - I pick my scope based on what I need to be able to see, or WANT to be able to see at the range I'm shooting, not based upon what rifle it might be riding.

You've probably been around here long enough to have noticed that I tend to prefer to be "over magnified" compared to most folks. If I'm shooting 600yrds, then my scope will have a top end in the upper teens or twenties. I CAN shoot and have often shot a 3-9x40mm scope that far, but I DO shoot better with a scope that lets me zoom in closer. The downside of a high mag set up is that it lessens your field of view, reduces light transmission and makes you more vulnerable to distortion. As such, I tend to favor 30mm tubes and 50mm objectives.

So, for my hunting at 0-500yrds or 0-600yrds, the Leupold VX-3 4.5-14x50mm glass is what keeps me happy. It's a little low on mag power for what I'd like at long range, but it's just enough to keep me happy, and has a low end FOV that's very functional. The Leup VX-3 6.5-20x50 is another scope that I have used for longer range hunting rigs, but the 6.5x is a lot to deal with inside 50yrds (very small FOV).

A Bushnell Elite 6500 4.5-30x50mm would be another good choice. The Leup is better glass, but the Bushnell is about $150-200 cheaper, and has twice the magnification range.

One thing to consider also is internal adjustment. That Wby Mag is pretty flat shooting, but 600yrds is a bit of drop to account for. For example, some of the Nikon Monarch models used to only have 20MOA of internal adjustment in high mag scopes, so they'd limit your range unless you set them up in an angled base/mount, or in Burris Zee's.