Yes you are right. I guess it's been a while but here is a link to a thread about that 6.5 and a borden rifle chambered for it. I know the author is willing to help people out and I believe he has dies and reamers for it- just join the forum and contact him
6.5 EXTREME, Borden Timberline - Alberta Outdoorsmen Forum
I've got a bit of a 6.5 addiction as well, would you mind sharing your 6.5 WSM experience and how you found it a bit finicky. I'm on round 2 with a 264 win. I found it a bit finicky to keep the es low when I was playing with my first one. Retumbo and 140 vld's.