...well being 'old school, shoot the biggest bullet you can shoot well' & a firm believer in hydrostatic shock, I'd see if I could get him shooting the .325 WSM w/ a 220gr. Sierra SBT (B.C. 0.521) over 63grs. of RL-17 @2800fps., ballistics wise, right up dere w/ the 8mm RM or .338 WM 210-225gr. loads w/ less recoil & a lot less muzzle blast. Lower end, I'd work up loads for the 7-08 or 6.5 WSM w/ heavier bullets. If one bullet did it all, we'd all be shooting 'one' bullet, but lighter bullets are generally designed/ constructed to perform on lighter targets. Elk bones, even the ribs are easily 3X the size, mass, & density of deer, a tougher bullet is probably a good bet. Personally, I'd feel a lot more confident in a 165gr. in the .308, a 160gr. in the 7mm, any extra 'drop' will probably be offset by less windage, 'drop' is easy, wind is always the bugaboo...