You might want to check on a couple of your custom barrel makers to see which of them have the 6.5/300 WSM
reamer on hand. Then you could buy your barrel chambered and save a slug of $$.
This caliber has always interested me. It's on my favorites list.
One day my 270 WSM will head this direction.
If you search this forum for 6.5wsm you'll find old posts.