Yeah, you defintely will need to level up your chars a lot more than what you have them at now...no doubt. I just accepted the Yiazmat hunt today and took about 4 Mil off him in about half an hour's time. My levels are 83 for Balthier, Vaan, and Basch.
that's pretty slow.
I just have the classic basic gambits for my party ( buff , attack and so ) , so I need to do everything ( decoy, reverse, curaja when I need , etc ) manually, cause they are very "delicate" skills to hang. So that swallows me lots of time ( I have the option of battle pause when I choose what to do with my characters too ), even so.. it took me like 4 hours the take 75% of his HP.
Right now there's like 5 bars left and I got angry cause he gets insanely annoying ( not hard ) so I'm cheatin ff12 with KH >=(
Later I will beat him, but I guess it's goin to take me more time than I thought.