I would fully expect us to be changing shape from 352 to a 442 or 4231 with McCormack part of the 2 or middle of the 3.
Tait aldred Dunne/Hartley dunne/livi/ATS
Ariyibi Campbell Turnbull Hastie/frear
McCormack main
Prefer dunne at CB but may be better off using him on the left for now depending on how ready livinstone is, or uninjured ATS is. I don't see main getting dropped, but if he does, maybe McCormack as the 1 in a 4231 with Turnbull middle of the 3 and mchugh in with Campbell.