According to the piece on Smith in the Australian Dictionary of Biography by E.D. Daw:
Using a borrowed Napier seaplane engine, Smith and Harkness began building a better racer, the (Sir) Fred. H. Stewart 'Enterprise', named in honour of their sponsor. Delays occurred when they disagreed about its design and Harkness became ill. Their differences came to a head in New Zealand in December 1931, when Smith altered the car. Harkness began legal proceedings in Sydney, but later settled out of court.
That explains the cowling shaped for the Lion engine rather than for the V format Royce engine of ANZAC.
It is not helped by internet entries that do not recognise that ANZAC and Enterprise were different cars albeit both having various shapes of bodywork. The wheels were characteristically different between the two cars.