If you scrape the crud out of the hole just above the green arrow in the third pic you will find the end of a dowel pin just below the block casting. If that pin was driven in at the factory it would have had large lines going to a full flow filter in canister mounted to the intake manifold.
This engine was not set up for flow flow filter. If you have the pin driven in you Must have external line to bring oil to the galley.
