8 twist is minimal if your wanting to go any heavier than the 80s. My smith just finished my 22-6.5x47 lapua and I broke the barrel in with the 90s. The 90s would not stabilize. While they didnt completely keyhole the bullet holes were easily distinguished in size from the holes left in the target by the 80gr bergers.
I admit that I know just enough to be dangerous.....but dangerous at ever extending distances.