If the event you're anticipating is shooting in self-defense you are best off with a rifle that you can (and
will) shoot multiple times without lifting your face from the stock. For most people that means a semi-auto or a pump gun. This is
much more important than having extra power.
The reason this is important is because the moment you lift your face from the stock you'll start missing and shots that miss don't do any good.
A .243 that you score multiple hits with fast is 100 times more effective than a .45/70 that you score multiple misses with slowly.
One of the old Ruger .44 Carbines would be fine - very handy, easy to use and sufficient power.
The Remington semi-auto and pump rifles come in some good calibers too.
Personally I would choose the .243 simply for ease of control during rapid fire because the ONE requirement you must meet is to score a hit or hits.
Of course lever-guns can be fired fairly rapidly without lifting one's face from the stock -
BUT -
that takes practice, especially to be reliable under stress and
most people are not skilled at it and have the natural tendancy to take the lever gun away from their shoulder to operate the action between shots.