Re: 270 Dakota
From what you have stated now, I would go with a 280 AI hands down. You can get 160 gr bullets to 2950-3000 fps with a 24" barrel. Nosler is making 280 AI brass now. That would also be an advantage as you do not have to do any fire-forming. If you wanted to drop back to 150 NBTs for use on hogs and such, you should be able to get a hair under 3100 fps. Hornady makes their Interbond in a 154 gr bullet, and if that shoots well for you . . . . They also make a 154 gr SST and 162 gr AMAX. You could just buy a bunch of Hornady bullets, but I have heard some folks express concern over air pockets in the Interbonds. If that was a concern of yours, stay with the 150 gr NBTs and 160 gr NABs. Of course you can always play with the heavy SMKs or Bergers when you wanted to really strech things out.
I know it is kind of an forgotten round, but a 7 BooBoo would fit the bill. It has the capacity of the 300WM without a belt; however, you are stuck with RWS brass which is as pricey or worse than the Dakota but top-notch.