I've done 6.5-06 on 8 twist, 260ai on 8 & 8.5 twist, all run under 2900 fps. Given the velocity advantage of these, I can say that 8 twist will work for you well, and 8.5 will likely do the same.

Originally Posted by BrentD

I would not buy something that runs on any kind of primer given the possibility of primer shortages and even regulations. In fact, why not buy a flintlock? Really. Rocks aren't going away anytime soon.