Gospel, +10 STR food, and all the buffs, including WS ones. There are other foods which add ATK too.
Equip wise, shackles + bloody iron ball, whisperboss/aliot manteau, greedy alice doll and tarou ring, overupgraded BR/slotted infi, evil wing ears(?). To get EVEN higher ATK, get a clown + gypsy to ring of nub and drum on the battlefield.