Patrick,
It looks like you have a 1955 block (the photo of the block date code is a little dark). That engine would have a by-pass oil filtration system.
If the holes on your block are in the same location as on a 1953 block,
this diagram might show you where the oil lines attach to the block.Here are oil line locations for a 1954 235 block. There is no dowel to push in or out in an engine that uses a by-pass oil filter. That is only pertinent if you have a 58-63 261.
Tim
