You are correct on the 73-200 operated then by a bunch of 'seagulls'. even philvang had to throw rocks to get them airborne!
I was thinking of the -500 that could operate from from most of the PNG strips, giving good load factors using low-pressure tyres. (The -300 appeared a better performer but at some 2500ks+ over the -500, would seriously reduce payload ex HGU) Mt Hagen has been lengthened, Rabaul-Tokua no problem though a bit narrow; Hoskins ok, Buka I think ok. Madang is a bit short so is Wewak. Goroka was out due to sfc and slope though I am sure that the manufacturer could come up with new fugures if needed; Kavieng could be ok, Manus no problem, Vanimo ok.
I believe that the F28-100 needs more runways extended that the 73. So let's see what happens in future months and whether APNG will test the 'open sky policy' of Dom Polye.
For me I'd put it over the density routes of HGU, LAE, RAB-TOK and HKN to test the water.