I have a Model 70 in .300 Win Mag and love it! I would however agree with the other posts and suggest something like a .35 Whelen, or .45-70. Your '06 loaded with Federal HE, or Hornady Light Mag. would be right on the heels of what a .300 Mag does. Just like in stocks, it is better to deversify. A good varmint caliber is always a good choice. If you really think you need more knock down power, then I would suggest stepping up to .338 Win Mag. Ask any Alaskan Guide what the most versitile caliber is, and almost to a man they will say .338 Win Mag. Better yet ask them what thier personal backup rifle is, and I can almost garauntee it is will be a.338 Win Mag. It is a bit more recoil than you are probably used to, but not unmanageable. I am only 5'7" and 165 and can shoot it very well. I really like the .45-70 in any of the new lever actions available, especially when loaded with the hot loads from Buffalo Bore. They will handle ANYTHING that walks on our continent, and almost any other anywhere else in the world!