The RAAF Aeronautical Information Service produces Enroute Supplement type books, one for small strips (less than 3000 ft I think) and one for the larger ones, covering PNG. They are for military use, but given that they work pretty closely with airservices in this department you could possibly buy one if you contact them via the number in the Australian ERSA. Worth a try anyway.
They're very handy for PNG and fairly accurate.
Unfortunately I had to give those books back or I'd just quote the info straight up.