358WSM,
If you're trying to keep recoil to a minimum for the purpose of not losing your sight picture during recoil, a 25-06 will bump too much and you will lose the picture unless you use a heavy barrel.
I've learned not to assume MOA loads at100 will hold within MOA at 400, so to see which rifle/load will actually group better at 400 or 500 is the only way to really know. My vote would be 140 grain .270
