Thanks to Rick and Mark IV for the information and questions to help me determine if this is a true S.O. and it's origin. This was purchased as a block only. I did some research on the oiling flows for an S.O. On this block, the
oil leaving the filter enters the supply hole in the block and turns upward until it intersects the tube shaped bulge running from the front to the back of the block. There is what appears to be a casting flaw just above the pan rail on the R-H side of the engine. There was a very small pin-hole in the block that I repaired. I am not sure what to look for on the casting code. I have attached additional pics.
http://s1083.photobucket.com/user/aug41979/media/IMG_2642_zpsoawx8h81.jpg.html?o=76