I know that he's a toughie so it will probably be high but for those who have beat him what level should I be at to stand a chance at winning?

I beat him around level 75, and I had no trouble. I think his level is 55 or something close to that. So I would think that if your main party is at least level 60, the battle could be kind of challenging, but very possible.

65 is already good enough. It took me about half an hour.

Easy easy battle, he barely does anything threatening, just takes a long time. Some parts are frustrating where he has annoying attack pattersn, but they change every few bars.

But you should cherish the segments when he uses "Invert". Refills your MP fast, and you immediately get healed if you have the Curaja gambit.