The 270 will definitely work, in december of 2009 I took a cow elk with the 270 150gr Nosler Partions. It was a one shot kill and the elk dropped about 35 yards from where I shot it.
One of my buds guides and his clients bring in all kind of cannons to hunt elk. He ussualy take his clients and sets a 1 gallon water jug at 200 yards. He has them use his truck hood as a rest and sees if they can hit the jugs. In some cases they cant, and then he has them try out and use either his old 270 or 308. When it comes to elk, it shot placement that is the most important thing.
