Hi Doug,
For Rarotonga sportfishing, a small scale but very skilled guide is Pupuke Robati Jnr. He has a basic potimarara wooden boat but I have heard outstanding things about him. (one example while jigging, he can actually 'hear' the fish making a grunting noise through the braid line and therefor picks it for a GT mid fight)
Have a great trip, the Cook's would be a wonderful place to visit (and fish a bit) Raro, Aitutaki, and beyond...
Cheers David