I would ask the Perth groundsman to create the greenest wicket possible, play 4 seamers by dropping Doherty for Mark Cameron who has been superb this season for NSW, bowling average of 11!
Drop North. The lad is suffering now, and cannot be exposed anymore at this level. As good a murderer of State sides that he is (a la Ramps), against the Worlds best simply cannot cope. Bring in Khawaja from NSW who is averaging 70+ this season.
The final decision is the most difficult. Who should replace Katich? Common sense says Hughes as he has been the man waiting in the wings, however his form has not set the world on fire. It would be a wildcard, but move Hussey to open the batting with Watson, who has done this before and bring in Cameron White, who scored a 100 against England XI for Aus A.