You might consider a Range Certified Weatherby Vanguard. They come with a Sub MOA guarantee and factory shot target that usually measures less than .7 MOA and sometimes better. No other manufacturers other than Cooper provide a factory shot target or accuracy guarantee.
They are an excellent platform to customize from down the road. The action has an integral recoil lug, one piece ported bolt with M16 style extractor. They have an excellent 2 stage 3 position trigger, however it can only be adjusted down to 2 1/2 - 3 lbs. After market options are available if you want less pull.
The Stock is a B&C pillar bedded stock which would also be good for a future build project or you could sell it and upgrade to a full aluminum block or a Manners or McMillan.
I currently have 3 build project in process. 2 on Vanguard actions and 1 on a Rem 700. The 700 has cost me a lot more than the Vanguards to upgrade, i.e., new bolt with extractor kit, new heavy duty recoil lug.
With a good bullet and a good load you could hunt deer to 700-800 yds with a 308 Win, With a 300 WM you could exceed 1000 yds. The 308 would not need a brake. A brake would be very helpful on a 300 WM. The 308 would be a little cheaper to shoot and much better barrel life. The 300 WM would buck wind better.
You should be able to get one off the shelf for about $900
Hope that helps and good shooting