8 twist in 223 should work fine for anything from 40-45 grain up to any 80 grain bullet. I shoot 52s in my 6.5 twists quite a bit so don't be afraid of the light bullets as mentioned.

Along the way try out the 75 amax as a heavy hunting projectile. Its worked very well for me. Probably because I can't drive it fast enough to make it into and explosive round, only one that opens reliably and is accurate for longer ranges. A coyote the other morning never knew what clipped him out the side door of the house at about 200 yards when the 75 got there.

Jeff