Heavy
Even with the heavys, a 270 is fast, so pick the one that will hold up best. Like Mt Goats, they can absorb a tremendous amount of lead, then dissappear into places you don`t want to look for them in.
Hard to beat a Nosler Partition for terminal performance but frankly, I`ve found few rifles that the Partitions will shoot well in. I`ve never had Partitions shoot less than 2 inch groups in rifles that normally shoot under an inch. If you konw you`ll be close, a Partition is a darn good bullet and I`m not repeating what I "heard somewhere". I`ve used them, just not at long range.
If the critter is going to be at 250 plus, a BT is not a bad choice because the bullet is going a lot slower at that range, hence, you are more likely to get good expansion. A heavy bonded bullet at long range often will just punch two holes. I use BT`s for most all my game.
And, of course, shot placement is everything.
Good luck,
Bear