you finish normal , by completing act 5, lv 56-57.
No need to get trouble about lvs in normal, just doing the quest will be enought. its same with melles and mages
Now the epic/legendary, its not matter the lv, but by the equipement. most of the players tend to farm bosses to get their proper armor and weapons, then just move on.
but with no farm i think you can end at lv 75 at legendary.