spd,
Sounds like you have made up your mind but I just wanted to throw in again.
You are looking at the wrong numbers.
And I assure you a 150gr 30 cal bullet does not have a higher SD than a 150gr 270 cal,
a 150gr 7m-08 or a 180gr 30-06 (the educated hunters bullet weight choices for elk in those calibers).
Trajectory and energy figures (within reason) don' t mean much on an elk. It is all about bullet construction and penetration and where you shoot the animal.
You are lucky enough to have what some consider the perfect caliber for elk, hunting why handicap yourself by not using the proper weight bullet? Be all you can be!

When people say elk are tough it is not an exageration.
I killed a 6 point wounded bull a couple years ago that a guy had shot a mile away from where I was. This bull had run a mile and was still going with a shot through the antler one in the stomach and the entire right rear hip joint and quarter destroyed from two shots from the rear. There was also a glancing shot through the front left shoulder which I imagine was the first shot but it was a little far forward and obviously from an bad angle.
Then the guy who had shot it 4 times didn' t even come looking for it. Hard to say for sure but from looking at the bullets I found I think he was using a .270.
Good luck on your hunt either way.