What you are shooting will work fine. If you are looking to make a change however- I love a 165 grain in the 30-06 personally. The 165 hits the sweet spot between flat trajectory and maintained energy down range.
Perfect round, but I've had bad experience with some core lokts separating. 150gr Barnes ttsx would be my choice. Yearling bison should be similar in size to beef of the same age, I'd guess 500lbs or less. There is a lot of good fantastic meat there, go for a headshot.