I would agree with the above commenter that the 150 grains would be a good choice because the will shoot a bit flatter and will hold sufficient energy out at 300+ yards, but don't overlook the 168 grain loads.
Where will you be hunting out in Wyoming? If you're hitting up the eastern plains you might want something a bit heavier than 150 grains to deal with the wind. If you're going to be hunting north or west of Rock Springs then the 150's will be just fine. Regarless of the grain, the Winchester BST's are my personal favorites. Have fun and thin out those herds!