Black bear;
I am with you on the 9.3x57. since we don't really have huntable bears in Texas, I haven't had the opportunity to use the 9.3x57.
Alaska in the early '70s. One with the .44 mag and the other with, don't laugh, .243 Win. I wasn't really hunting spring bear that day. I was looking for food targets of opportunity. Porcuipine, hares ( hard to see in the spring with no snow, or just being prepared for the chance wolf, wolverine or the menecing pack of wild dog. I had a 6 power fixed scope on the Remington 600. The bear jumped out of a hole in the side of a path. Someone had buried moose guts the winter before. I brought the rifle up and all I saw was black hair. I could not see where on the bear I was aiming. I didn't shoot until he ran down a draw and started up the other side. One shot between the shoulders. He was about 200 lbs. Pretty typical of the area.
I would use the 9.3x57 or .45-70. I would love to see also what my 16ga x 12.7 MM SXS would do!! What fun.