.22, 12 Ga. ,223 and 300 WSM would take care of everything in North America. I would settle for an 06 or 270 for my big rifle but many think you must have a magnum.
I do not much bird hunting any more but I still consider my shotgun the best home defense option. Although I have other guns I could get along with my 22, 12GA 22-250 and either my 257 Roberts or my 6.5x55 Swede. I would keep the Marlin 45-70 for a possible moose or Bear hunt.