Some people beat Vegnagun at 40 but at 60 you would be sure to beat it. He is not that hard actually. Oh, and when Pacce finds a new dungeon in Bevelle, you do not need to finish it to complete the game, you just need to go up to level 20.
After the 40th floor that dungeon gets much harder than beating Vegnagun...
And right after you defeat Shuyin and you are back to the Farplane "flower carpet" you need to press X twice and answer yes to the kid fayth. Then just relax and enjoy the ending (there is a surprise after the credits roll, but only if you press the X)