The intended party for the big game is:
Melee: Kalinn 11, Bren 12, Borric 10, (Drev effective 8+), Shadow(wolf) 11
Sneak: Fury 11, (Aradra is super stealthy too if he wants to be)
Arcane: Relic 10, Anaerion 9, Sylvain 9
Ranged: Aradra 11,
Healing: Bren (effective 8), Relic and Aradra are wand capable
Buffing: Elenka 8
Still a maybe: Daylily 10, Cythera 11
Everyone is drawn from Forbidden Isle of Ancient Secrets, Unwanted Farmhands and Coils of Flame. Elenka will most likely level after the first fight.
This is a published Paizo module. It was for 3.5, so I have to adjust a bit on the fly, but that isn't difficult. But, being module length, the game will probably run 18-22 months based on my experience with Forbidden Isle. The characters will level 4, maybe 5 times. jkason is the judge.
Edit: I just thought of something extra. Instead of sidelining Arianna for a while, I may NPC her, and simply use DMCs to keep her leveled up so that keeping up with the others. The reason why is the next highest level adventure will be 8th by JS45, and both of my eights can't go into the same game there. So, she will add a bit more melee and a bit of minor healing capabilities.