From PRT continue to track north to Pennant Hills and call Syd Terminal 135.10 for clearance. They'll give you a code and palm you off to Syd Departures at LRF on (I think) 123.00. Thats if your gonna do some laps in the Harbour.
Otherwise you can just remain OCTA and track down Victor 1. Just remember to broadcast on the Victor 1 frequency.