.290 is the standard neck for the 6.5 for 1k BR guns and you are right it will require neck turning. You will have to do extensive turning to get there (down to about .012 or .0125, but as long as you understand that, then no problem. I would go with the .012, gives you a little more margin of error if you are new at this.
Mike Bryant is building my new 6.5x284. He has a reamer with a .290" neck and a throat set-up for the Sierra 142SMK so that is what I went with.
I just ordered some Lapua brass, dies, etc and was wondering how much I would need to turn off the necks.
Looks ike about .003"-.004" will get turned off.