They're a mid to late J type smogger head but with a good exhaust port and (IIRC) a lower volume intake port with a raised floor. A good on a budget iron head and even decent for a 318 build. I came across post by @MOPAROFFICIAL a couple of days back that I cannot locate now where he touches on the J and some of the decent later smogger castings and covers some of the different quirks. I'm hoping to find it again because it explains more than I can remember at the moment.
