As far as the Japan War effort is concerned Australia might as well be located on the Moon. That is how hard it is to get the neccesary forces down there to sack the captial against a smart Allied player. To make matters worse Australia is easily reinforced by American Fighters and can be subject to liberation by America as well. India on the other hand is not so easily reinforced by the Allies and once it is taken over by Japan the USA is not going to be able to get down there to liberate it.
I think it makes more sense to try and take Hawaii and India. It is up for debate which one Japan should take first. I think it depends on a variety of factors in choosing the first target but most scenarios will lean towards taking India first. China can be marginalized on the way to India thus insuring the safety of the victory cities in mainland Asia. China if not dealt with correctly can easily cost the Axis the game period.
Taking Hawaii will be a tall order at that point but Japan will at least force the USA to heavily reinforce Hawaii which may open a window for the Axis to win in Europe.