I'd get an '06 and load 150s for deer, 180s for elk. I happen to like the Sierras, having had very good success on deer with the 150s. Great sub-MOA accuracy.
Meddling around on my 500-yard range, I found that the trajectory of the Sierra 180-grain SPBT was quite near that of the 150-grain. Based on a comparison of "depth of dimple" on the steel plate, I'd expect excellent penetration by the 180 in an elk.
You're from BATFE? Come right in! I use all your fine products!