Maxed solid 60fps I would guess unless they finally updated their engine (I doubt it), so yeah you should be fine. You only said 6900 series so you could have either a 6950 or a 6970 but either way maxed shouldn't be a problem.
Supposedly they have made some improvements to their graphics engine, and have dropped DirectX 9 support for Black Ops 2. Even so, I think your system will have no trouble running the game. You'll probably still be able to max it out.