just my 2 cents. If your gonna shoot 180 gr.bullets out of an 06' case why don't you just stay with 06'? The reason most people shoot 338-06 is to launch heavier bullets, with better sec. density, bal.coef, frontal area, for more ft. lbs of delivered energy, and momentum at bigger animals like the elk you are building the rifle to harvest.
I built a 338-06 ackley and shot 250's @2,550 out of 24" barrel. good trajectory to 400 yds, and plenty of juice with great bullet. Never shot anything ever more than once, never lost game.
The way I see it, velocity stops at the hide. For elk you need a heavy for caliber, deep penetrating bullet with high sec. density, that will plow through thick heavy hide, bone, and muscle while delivering a heavy blow to the vitals, even on less than perfect shot angles.