Re: 6.5-284 build ?'s
Having built a number of them and currently using one as my main LR rifle I think you are getting some good advice here but a .296" neck is going to require you to turn neck on Lapua and W-W brass. I don't use Norma brass so can't comment on that. The smallest neck I would go with plans to NOT turn brass is .298" and .299" is safer.
I have a .297" neck and on some lots I have to make a skim cut to get good bullet release.
For a field portable hunting rifle, I use 25" barrels. I can still get 3000 fps if that is my goal and is a little stiffer and lighter.
My preference is for an 8.5" twist. It will stabilize any bullet commonly used (142 SMK, 140 Berger etc). It is more forgiving when shooting the excellent 130 grain bullets though. I push these to 3200+ and jackets can start to come apart at 3250.
I am using an 8" twist Shilen on my current rifle and it shoots bug holes. Shilen does not make an 8.5" twist. As far as barrels are concerned; any of the name brand quality barrel makers are going to make barrel that is capable of shooting better than a repeater 700 action is. Don't get too hung up on it. If you building a 1000 YD BR rifle or a competitive F-class rifle (all single shots of course) you can sweat the details a little more.
I like the McMillan Hunter pattern stock. It has a palm swell and a very beefy forend and can take up to a #7 contour I believe. I use #4 myself.