I need to correct my previous posting...
After thoroughly cleaning decades of dust and grime from these heads. I have discovered that the ports were actually filled with something such as Devcon and then sealed with silver paint. It honestly appered to me that they were cast this way initially. I certainly apologise for misleading anyone with my prior description of these heads.
I am still curious about the statement on the CRG ZL-1/COPO page describing ZL-1s as not having these crossover passages, a heat riser valve or carb choke... Is this actually true
I am still interested if anyone may have some info about the work done on these heads by Batten and/or Elkins or where these heads may have been used. I think they may have an interesting story to tell if I just knew who had used/raced them in the first place.
Again, I apologise for the confusion.
I attached some pics if you are interested. I hope that you will be able to see the details.
The Batten Heads logo is located just above the 71201 stamp. It is extremely fine lettering and was stamped very lightly, so it is somewhat difficult to see well in the photo. There are some additional numbers that I neglected to mention before, they are 3372 and 3373. One of them is stamped onto each head. The numbers 1 and 2 is stamped on them as well. Could any of these (or others) be useful serial numbers ?
Thanks again, Rick