Best have a search on the Dununda forum when it isn't locked. There are plenty of threads about it.
Don't expect a lot and be prepared to move. 650 hours is good but not that great for Darwin. 650 hours is good for Kakadu, Kununurra and Broome and other such places.
What are your hours on? C206 time is good. If no time on those, then be prepared to wait a bit. March is getting "late" so I would be very smart as to who you approach.
Use the yellow pages online to find out where the scenic/charter operators are. You may be lucky and score a twin job in Darwin but don't count on it.
good luck