if you are keeping your shots under 300yds then the 30/06 with 180 gn. accubonds is good for anything with antlers.and i ALWAYS have a full freezer to prove it.i have used mine on quite a few elk,deer,antelope,blackbears,caribou,and a pile of african plains game.and have always been imprested with bullet performance.
but if you have to have a new "elk" gun then think about the .338 win mag.or for a bit lighter recoil the .35 whelen. there both a real power house and a great insurance policy if you hunt in a grizzly bears back yard.
i think you will find the .325 to expensive to shoot alot and hard to find ammo for. and unless you shoot the 45/70 alot and really know its ballistics that 300 yd cross canyon shot is going to be a crap shoot with a short barrel 45/70. but the up close "dark timber" stuff i can think very few guns i would rather have.
good luck and hunt safe.