All my characters are level 47 or 48

Ingus thief job level 99
Luneth ninja job level 20
Refia Summoner job level 18(all summons)
Arc Devout job level 20(all spells that matter)

I use a thief because they are always getting better equipment
Ninja is just super powerful
Bahamut(duh)
Healing(double duh)

do you think I am good enough to get to the final bos and beat the bitch