I am preparing to rebuild my spare 261 to replace the stock one in my Canadian 1962 Pontiac wagon and as per someones advice I began searching for a 235 cylinder head with the 848 casting number to install for higher compression. I found and purchased one and then began stripping down the spare block to get it ready. I discovered that my spare block (3769717) had the 235 head on it already (3836848). I then checked under the hood of my wagon and also found that the motor that I thought was bone stock had the 848 head on it as well. Is it possible that the Canadian Pontiacs had these early heads installed from factory? Or did I end up with 2 motors that had already been modified? I also am wondering how to decode the stamped number on the pad below the distributor, it begins with W9. Thanks in advance.. 

Steve