I've looked at their reward flights for SYD-HND and they are outrageous. (At least it's a day time flight so the 737 isn't too bad, but your direction is a red eye.)

It might also be worth pricing VA redemptions from NRT-MEL (on SQ) or SQ redemptions for the same itinerary (usually more points but less taxes and often more availability). Depending on your plans you could look at originating in KIX or FUK (I always wanted to say that). VA seems to keep the number of miles for a HND redemption high.

these latter options seem to be less miles and better product!