Here's what I got..67 gto..Mom gave it to me..I'm restoring it! I need to get the motor in before paint. It's mostly stock except the motor. The guy she bought it from put a 389 with 400 heads (670) on it. I put a demon 750 dbbl pumper on her and X piped the exhaust with 2 1/2 pipes out the back just because. Had it dyno'd and it puts out 255 at the tires. Not to bad..I want to put a 400 back in the ole girl and port and polish the 670 heads. I would like to get 400-450 Hp out of it. Is it possible? I need to know what I need in the 400 to get max horsepower! I only want to build it once..It's not going to get alot of drive time...Thanks for your help!!