4350 works well for 130gr bullets at decent, but not top speeds, but it wouldn't be my choice for loading 140gr and 150gr bullets to their potential. I got the best velocities with 150gr bullets using Reloder 23 and 26, I'd probably start with RL23 (good velocities and temp insensitive) and 150gr bullets and see what my accuracy load clocked at. I was at 56.7gr and over 2,900 fps in a 22in barrel with my load work up.
The only elk I shot with a .270 was with a 140gr Accubond over 62 gr of IMR7977 for 2,930 fps out of a 22" barrel. It worked fine, but if I was working up an elk load for a .270 now, I'd lean towards the 150gr Accubond introduced this year, paired with RL23 or RL26.