Before you worry about it from a damage perspective, I'd suggest watching a video of the final fight on youtube. The fight is very similar to some WoW fights, but success on the boss relies heavily on the tank positioning the boss correctly. My suggestion is to make sure your tank keeps his back to the perimeter wall. This will keep most of the acid the boss spits out along the wall away from the party. It's important the boss does not touch the acid, as it will heal him, and it will hurt you guys if you stand in it.
Overall, either job is fine to use. Just make sure everyone knows the fight.
Winthorp Donaldson: Monk. Pally, Scholar, Summoner, White Mage (Ultros Server) (FFXIV)
Arbelas: Sith Marauder (SWTOR)
Doctor NewJersey: Lvl 30 Mental Controller (DCUO PvE)
(ret) Wlnthorp (Fenrir): FFXI
Part RDM, part RNG, part BST, part THF, part PLD... 100% jackass.
(ret)Eccoh: Level 85 Night Elf Druid (Ravencrest)
(ret)DaveTheGnome: Level 85 Gnome Mage (Ravencrest)