please help 225/318 swap

you guys have been helpful.Do i sound like im on the right track?am i wasting my time with the 904(because its an easier swap....right now).i love my dart and have wanted this car for about 15 years,one day just got lucky,and 1 came in on the back of a flat bed.all orignal,1 owner,lots of papers and 53,000 orig. miles. dont get me wrong,it needs work it sat for the last 10yrs. but it still runs like a champ,(even if it is a /6). theres nothing like the respect you get when you drive down the street ina mopar, and i just want better for my baby.