My reccomendation for elk with a 45-70 would be the Buffalo Bore Factory Ammo with the Hard Cast Bullets. They will out Penatrate all other Factory 45-70 loads that you mentioned.
Of the loads you mentioned, they will all kill elk. And like with any game animal, it's all about shot placement and knowing the range & capability of your ammo.
I consider my Marlin 1895 to be a 150 yard elk rifle, because of the low powered scope mounted on it, not the cartridge. There's lots of stories of the old time bison hunters killing stuff well over 1000 yards with a 45-70.
That's all well and good, but that doesn't mean that I'm that capable of doing the same. I know my shooting limitations, and sure as heck don't won't to wound an elk because of my crappy shooting ability at 1000 yards. .
By the way, My Marlin 1895 hates the LeverLution Ammo. Groups spread to 5" at 100 yards. Maybe it's just my rifle, but mine will shoot the 300 grain HP's into a 3-shot 1" group at 100 yards.
Find out what your particular Marlin shoots the most accurately and then spend some trigger time practicing with that particular load. It will pay of on a future hunt. Enjoy your new rifle & good luck on an Elk Hunt. The real work starts when you get one on the ground!
