Don't want to consider using Hawkeye decals?, maybe a bit of research would help
they have
DHC3 Otter CDS-030
PBY Catalina CDS-028
and DC3 CDS-207
Those plans say it's a 16"circle, maybe the 1/144 PBY Catalina might go close
Finding good close up images is difficult in that most aren't square on or even good quality given the time period and cameras of the day
Aussie Airliners is probably your best search area, found this of an DHC-3 Otter, not bad, not good either
http://www.aussieairliners.org/dhc-3/vh ... 0.013.htmland don't forget TAA was an early Twin Otter customer, found these on the Twin Otter site
http://twinotterarchive.com/DHC-6_6.html#VHTGR_1967http://twinotterarchive.com/DHC-6_8.html#VHTGS_unkLate Edit
Who did the Cessna 185 TAA Sunbird decals for the odd scale (old Monogram kit) and in 1/72 for the KeeKha kit, that would almost give you everything you need
was it one of those very limited Ronin decals from Roy at Southern Sky?