Have you looked at The 7mm info at 6mm benchrest.com?
There is a lot of good info there. Hope this link works.
And I was just thinking You might not need that much twist with a bullet going that fast. I put a 8 twist on my 7 saum and didn't need it.
To do it again, I chose a 9 twist. Just a thought.......................
7mm Cartridge Guide