Given the design of the dungeons and the ease of the boss fights, as well as the items and spells that increase base damage + haste. It's just a matter of getting enough life and healing to make it to the boss, power up with saber, steel, tmpr(whatever version your FF1 is), then attack and kill the boss. Given the relative high HP growth of Fighter this can be pretty low in parties with Fighters, such as low 20s.

More levels won't really help but to make you be able to survive longer in the dungeon.

Is only thing I hate about FF1... everything else i like. The dungeons are 3x as hard as the actual boss themselves. Just because of the endurance factor and lack of healing on Normal origins and original NES.

By the time your strong enough to actually make it to the boss, he's pretty dang easy.

Course this is probably a biased opinion, and I'm open to others.
I usually go with F, BB, WM, BM or F, F, WM, BM. F, Th, WM, BM. sometimes replacing the BM with a RM