Al, I'd never want to rule out Randy's flat base bullets as an option. They shoot too good, even at 1,000 yards. He recommends not using a twist faster than 1:9 if you're going to ever use the heavier flat base bullets.
http://www.bibullets.com/products/
I have an email from R.G. where he placed second at a sanctioned
group match shooting at 200 yards, with a 121-grain flat base bullet, driven by a Dasher. PPCs had to read it & weep.
My guess is that a 1:9 will stabilize the 105-grain region BTs unless, maybe, it gets too cold. And yes, I know it is bullet length, not weight, that really matters
Far as that goes, Leonard Baity set a IBS 6 (or maybe 10) match aggregate record at the old Hawks Ridge club (in its heyday, with many of the best shooters in the East), using the 95-grain Berger.
But to BigDog, look: it's a compromise rifle. Where do you want the compromises? If we're going to make your compromises for you, where do we stop? Help picking a wife? -- almost as important as a rifle.
What's the rifle going to be used for? What are you most willing to give up? Most want to work well?