Re: 168 or 175
Yes Johnboy is right on. Rule of thumb is 168 to 500-600 tops, 175 past that. Or a 155 if you have a slow twist. If you want a do it all go with a 1-14 tw and shoot 155s, or a 1-12 and shoot 175s. That's what most people do.
I shoot a 208gr Amax with my 1-11tw 28" Hart barrel. I'm using RL17 and hitting 2800fps (5.75MOA drop to 400yards, do the math if you don't believe me). Can also try the 190 VLD, or 210 VLD. Those all work great for hunting. For targets you can also try the heavy SMKs.
Powders to try would be VV-N540, VV-N550, RL17, H4350, and W760.
Hope this helps,