Fuzz1, I have a keen interest in PNG and basically wanted quite a few sim models specifically for PNG (Twin Otter, Otter, etc). If it helps here is what I have and have found over time for PNG in addition to the ORBX Vector, Global:
First I have particular focus on the CalClassic era or 1960s and earlier. If you get all the packages from Cal Classic you will find in their Asia Pacific Pack quite a few PNG airports including Moresby which by the way are very good renditions of the airports of the period the only one I don't use is Rabaul because it now ceases to exist. The additional bonus is that if you get their AI stuff you will also find they have done a very good coverage of airline schedules traffic etc for that period, so not unusual to have DC-3, F27's Electras etc out and about when you fly in that area. But not everybody's choice. I have spent about two years backdating FSX because that is the era i am interested in and the sort of aircraft I muck about with. ORBX can also come up with some surprises.
If you want to tie some of this together the Emerald Groups Solomon Islands scenery is good (combined with the WW2 stuff available via SOH) and OZx's Torres straight is also excellent. Little about for the Indonesian side alas.
Anyway here is what I have for info:
aimoe,
boram,
emirau island,
frieda river,
Garden Island
Green Island
nadzab
Peleliu Island
PNG Airports Pack (AYBK, AYCK, AYDU, AYGA, AYGN, AYGR, AYKA, AYKI, AYKM, AYKV, AYKW, AYMD, AYMO, AYNZ, AYPA, AYTB,ATYK, AYWK)
Plus what is in the Cal Class Asia Pacific Packs as well. (Nadzab, Lae Rabaul, Madang, Port Moresby)
In addition I have the ORBX addon - Tapini.