I recommend you try Firebrands every level. Whenever you can hit them enough to keep them frozen most of the time, you should get wonderful EXP from them. Also, if you have any points in MP Eater, you will rarely use MP potions because they have ridiculous amounts of MP to steal. 
I do remember training on Zombie Lupins a bit in my 70s. The best thing about it was that I could sell all of their drops for some extra mesos or NX... don't remember the EXP being particularly awesome, but it was good if I had a Hunter or another magician to split the map with.
I do remember training on Zombie Lupins a bit in my 70s. The best thing about it was that I could sell all of their drops for some extra mesos or NX... don't remember the EXP being particularly awesome, but it was good if I had a Hunter or another magician to split the map with.