318 vs 360

I'm taking on a project and trying to decide the route to take. I bought a 72' Gold Duster with a low mile original 318. I really wanted to find a 340, but did find a 360 with the 340 J- heads and a rebuild kit along with it. Taking my mopar friend's advise, I brought it home. Now, I'm not gonna drag race this car in the future but what I'm looking for is performance. Is it possible to get close to 400 HP with a 318 with what I have? Do I build the 360? Do I build the 318 and keep it in?