In our various 6.5's I've tried the 156 gr Oryx, 156 gr Vulkan and 155 gr Lapua Mega bullet and they all produced fine accuracy. All were 8 twists but I bet you'll be fine in a 1 in 8.6 with any of them.
When I had a Ruger 77 Mk II in 30-06 I had a great load with Big Game and the 150 gr E Tip. Had excellent results as well in a 303 British, 358 Norma, and heavy bullets in 35 Whelen. It's a good powder that does well in a lot of different applications.
An old thread come to life again! Since posting 11 years ago when I had no experience with the 160 gr Partition it's now one of my favorite bullets in the 270 Win. Usually quite accurate and performs great on bigger game. Going to try them in the 6.8 Western this coming year when things settle down.