Yes, they are steel or cast iron rather. The only numbers on the front side of the heads are a very large "6" and a small "8". There is also a "Y" and an "x". I guessed that they are world heads from the large "W" under the valve cover and with the "S/R" but other than that I have no idea what they are supposed to be.
Have you looked at the front and back real closely ? I think there should be a part number stamped there somewhere. I have a couple of pairs at the shop I can look at on Monday. The S/R tells me it is either a stock replacement head or maybe an S/R torquer.
Advanced Automotive Machine
1971 Chevelle "Heavy Chevy" original owner
I had the same problem with my Sportsman II heads. On mine World Products told me there are no p/n's or other markings on the exterioe of the head, but if you remove the valve cover ther will be some raised lettering. I believe mine was I-37? This number will tell you the model, but not the chamber size.
OK, I finally found it. Looks like just a standard S/R head. Though I have no idea which size valves are in it as it is still mounted on the engine. I was told the heads have 2.02-1.60's but I guess I'd have to take them off to know for sure. Thanks for the help. Perhaps someone may have a suggestion for a better set of heads for my 302?