The 270 Wby is a fast round, so it's a very good idea to use premium bullets, especially if you're going to use it for elk.
I would use 150 grain premium bullets, and bullets that come to mind are: Nosler Partitions, the Barnes X (or TSX), and Trophy Bonded, and other similar quality bullets that hold together. You could look into the Accubond and Interbond, but I don't think they are available in 150 grain weights. Nothing will out penetrate a Barnes, so that would be your bet for elk, and it's still a great choice for deer, although perhaps a bit overkill.
The Hornady Interock Spire point is a great bullet, and I'm sure it could be used for elk, but I would recommend a more premium bullet such as the ones I mentioned.
Zachary