I think so. When I lived in Maine I hunted deer with my .243. Although I never got a shot, I visited a deer camp where there was a deer hanging from the rafters that dressed out at 240, so about 300 on the hoof. I looked at my little .243 100-grain round and thought, "Nope, not enough for that horse." But, that long 6.5 bullet would be just fine.
I remember the old Finn Aagaard tales of people taking elephants with the 6.5 x 55. Of course they were expert shots and put it right in the ear hole. But, the 6.5 has a reputation for unworldly penetration. In the .260 Remington, 1500 ft/lbs. out to 250 yds, so adequate for elk out to that distance and anything but grizzly to ranges beyond, with low report and recoil. An amazing cartridge. "Sweet spot".