I understand the appeal of a lever gun, I was once under the spell of a Winchester 94. Short, light, handy, easy to shoot (stop me if this does not sound like a 45-70). Practicality says choose a 30-06, it made a whole trainload of cartridges obsolete overnight, the 45-70 among them. If you don't beieve this, open up Cartridges Of The World and look at the Obsolete American Cartridges section. But it is a nostalgia thing, it's not a practicality thing.
The 30-30 has a flatter trajectory, more energy, and less recoil than almost any one of the old black powder beasts, the ammo is cheaper, lighter, and the rifles firing it are lighter and required less maintenance than any BP cartridge gun. And, as mentioned above, we tend to forget that the 30-30 really is a high-energy cartridge. And I cannot tell you how many elk were killed with 30-30s every year before elk became bulletproof. Within 150 yds, a 30-30 will harvest any animal on this continent, and has been used to do so (although it may not be a very wise choice for big furry toothy ones).
I believe you will find a 30-30 is the most practical choice. If you do decide to go elk hunting, you will want something that reaches out farther than a 30-30 or 45-70 can, because elk are not tame and they live in really remote places.