check out XPhunter's latest XP's both have brakes and are using Leupold Mark IV scopes. you can see them on the SP forums or he may post here if he reads this post. both guns are exceptional, You will also like the 300 WSM, I have a HS in that caliber, I will post a pic of it as well.
BLAS, I use Vias brakes. They are the best brakes I've ever used. I would use a Nightforce NXS scope, rings, and base if it fits your budget. I would go with one of Joel Russo's stocks. I am having a 300-WSM built too, however, it's a rifle. I am having it built around Norma 300-WSM Brass and the 125grn Ballistic Tip. What kind of bullets are you going to use. The 300-WSM is an awesome cartridge with great potential. The Norma brass is really uniformed. It sounds like it's going to be a nice project.
I am thinking of a 165 or 180 gr bullet . I have a 1-10 twist barrel.
I just bought a Nightforce for my 7mm STW a 5.5 x 22 x56
with a R1 recticle.
I would like to use a 3.5 x 15 x 50 R1 in the money falls Right.
I sent Joel an Email about a Yellow and Black Laminated Stock , Looks like a yellow Jacket.
The 1-n-10 is a good twist as it will allow you to try some of the longer VLD type bullets. There are a lot of good bullets available in .308 I have been trying several of Bergers VLD's from 155 to 210 and really like them.
As hshunter said you might want to check with xphunter concerning the brakes as he has used a couple of different ones.
I have a Vais brake on my XP in 7.82 Patriot and it does a great job in tameing the recoil.
Good Luck on your project