That’s the one! Thanks for that cdmurray.
Searching Choiseul Island brought up a heap of info. I must have been before the Japanese built their base just East of the river mouth and had also occupied Guppy Island.

I have some other interesting docs that came with this haul. A short handout page titled “Medical Gen on Life in a Dinghy” It outlines what a downed pilot should do when he finds himself adrift in his life raft.
Another item, a handout again, it outlines partial and total restrictions on bombing and strafing of Bougainville Island. Dated 22/12/1944
Cheers.