Well, keep a .270, and buy a .338 of your liking: .338 Federal, .338-06, or the ol' reliable .338WM (if you can take the recoil). More than likely you will end-up using one of the first two .338's for all of your hunting.
But, everyone should always have a .30-06 in a rifle battery. Besides, you can always go up and back to it in caliber (.338-06, and back to .30-06) with no modification to the action except for a .338-06 barrel.
