Tearing it down

4323302. just looked this # up. now I am convinced that this is either a 318 or 360 block. Now next question. Should I just look for an earlier year block and replace the block and get a set of J or X heads or run this block with the cam set up I posted. I do not want to waste putting these parts into this motor if it is a smog motor. When I bought this car 11 yrs ago this was the engine that was in it. It runs fine but I was looking to get more lower end torque and figured a step up in cam would get me there. I am looking at a set of J heads another member has for sale here and will pull the trigger on em if this would increase the compression ratio. The heads on this block are out of here. As stated before I maybe going in the wrong direction here but need some advice from you Mopar guru's. The heads I was thinking of using are stamped 3434375A which I also looked up and are listed as a 360 head.