Re: 270 Win or 30-06??
If it was me and I was going to shoot at longer ranges, I'd split the difference and get a .280 Remington, or better yet, the Ackley Improved version since it's no longer a wildcat. Just because the selection of high BC bullets is much better in .284 than in .277, and the .284 bullets are lighter with less recoil than bullets with comparable BCs in .308. The high BC is better not so much because of flatter trajectories, but more because of the wind-bucking capabilities for longer ranges where wind is the biggest hurdle.
"Neither sport nor art should be unnecessarily cluttered and complicated."
"I'd rather be called a redneck backpacker than a yuppy hunter."