I don't own a 7mmWby, but I am close with my 270Wby. Hunting white-tails with either of these is really just about ideal. I'd look at whatever shot best in your rifle out of the available 140, 150, 154, and 160gr loads (either factory or handloads), and use a bullet that is reasonably strong in construction, just due to the velocity. I'd consider the Nosler Partition, Accubond, or E-Tip, or any Hornady bullet in those weights, or a Speer flat-based Hot-Cor, or a Barnes TTSX. In the heavier weights, you'd be alright with less robust construction, but in the lighter weights, I'd go with a bonded bullet with a polymer tip or the Partition. Hornady is bringing out the GMX bullet next year sometime, which is lead free (like the TSX/TTSX or the E-Tip), and will be available in 139gr I believe. Overall, a durable bullet that shoots accurately in the above listed weight range should be fine.