Not sure exactly what you are asking, but they are a Shelby only head. Not from, or like, Edelbrocks, and not a direct copy of the MR head.
While they do have a direct link to the MR head, with MR sized intake ports and the huge machined combustion chambers just like the MR, they have (somewhat) revised ports and a raised exhaust, so calling them a copy of the MR can't be considered correct in my book. I think Shelby missed the boat here with the ability to produce a more modern combustion chamber, but they stuck with the old machined MR/HR/TP style.
Edelbrocks have stock exhaust port heights and cast with provisions and drilled for 4 exhaust bolts per port and smaller 45cc combustion chambers. Their Pro-Port heads are the same but with unfinished ports and valve seats to allow for custom work.