225 slant six rebuild/ power up.

ok so just desided to keep my slant six insted of putting a v8 in my 1973 dart swinger. so my question is what should i do to it to give it more power? the car has the stock everything in it. its auto and i want to make it stick also so need know how to do that and what i will need? and how much power can i get out of a 225 ?