First thing, it sounds like budget is not much of a consideration, which is good if light is important.
If 500yds is your max range, then you have a few options on how best to compensate that will still be more than sufficient.
I have and do use the z-600 reticle from Zeiss on their Conquest line, which I like very much. All balistic reticles are made for a particular trajectory profile. At ranges up to 500 yards, there is a lot of flexibility to being within an inch or two for drop, which is fine in the field. This reticle is basically set up for a bullet bc of .4-.5 at between 2800-3000fps. The trick is that the more you change the curve of that trajectory, be it flatter or more curved, focus on being on at the longer range for drop. The z-800 is meant for Ultra Mag type trajectories(not just longer range), and the z-1000 is actually meant for .308 based trajectory, which is much more curved. I believe the Z-600 would best fit your caliber. I have been very happy with the optical quality of my Conquests.
I believe you should pay as much attention to how you can accurately adjust for wind as a sheep hunter. Your caliber in many populary bullets can see 16-18 inches of wind drift in just 10mph, which would be common in sheep country. The Zeiss reticles have this built in as well, based on that same typical ballistic profile. Here you can't cheat, so I suggest seeing how close to your trajectory the reticle is and judge if they are useful. Not sure Swaro or Leupold even has a reticle for this, which is a shame in my opinion. Here is where Vortex shines, but their scopes are heavy.
Good luck.
