If you are talking two legged varmints, there is a reason the military is beginning to use 77gr. OTM. I've never shot it so I'm not sure if it will stabilize in a 1-9 twist.

Winchester 64gr Power-Point is designed as a deer load. Any load using Barnes TSX would be a good choice. Over penetration is not an issue if you hit what you are shooting at. If you miss, it's a problem with any load.