CASR Part 132
4.3 Carrying passengers
4.3.1 Limited category aircraft may carry passengers in a private flight, a cost-sharing flight or an adventure flight. Adventure flights are a popular tourist attraction and can offset the, sometimes considerable, costs of operating and maintaining a warbird or historic aircraft.
4.3.2 No more than six persons (including crew) may be carried on a WHR aircraft, regardless of the seating capacity of the aircraft.
4.3.3 If a WHR aircraft has a seating capacity in excess of six, an application may be made in writing, or as otherwise directed, to an administering authority for approval to carry a greater number than six. The outcome will depend on the type of aircraft involved and a comprehensive risk assessment that would be required as part of the consideration of such an application. Any approval granted will not exceed the aircraft’s designed seating capacity.
All legal on the face of it.