What action are you building on?
As for barrel weight, here
is a list that you can use to figure how much the barrel will weigh.
You should be able to get at least 1/2" groups with a good match barrel. 1:12 will handle 165 gr bullets, but I'd go with the 1:11 just in case you decide to go with heavier bullets later on.
If you are in north Idaho, have Shawn Carlock put your rifle together - he is also a member on this board.