When I was still hunting, back when I still owned a bit of land, I used the 45-70 almost exclusively for hunting whitetails. It's probably the best swamp rifle that you'll find. The bullet is heavy and not easily deflected by a bit of brush. I've used an original trapdoor Springfield, and a Marlin model 1895 that I bought new in the fall of 1975 to take whitetails. The 45-70 is also quite effective on black bear, should you ever decide to hunt them.
A side note, the 7.62X39 is almost as powerful as the 30-30, there's really not much difference between them other than bullet weight. A 7.62X39 with a 147 grain hunting bullet is just about as effective as a 30-30 with a 150 grain bullet. The ballistics are not very different.