I'm no expert, but getting a zc motor to run 13's NA would be hard...a 13.9 is doable all motor...but solid 13's??? getting b16a to run solid 13's still takes some work. Your looking at at least 2 grand for a rebuild with headwork, pistons, rods, balanced crank. You'll need to get cams for it...custom ground cams can be done but it might take some experimenting. Yes hks makes them for the zc...but they are about a grand, and they would be too mild for your application. If you really want to stick with a NA motor then you should start with a better base...me personaly I'm gunna go turbo with my zc...that's my way to the 13's. Good luck