small block oiling system

[66dartman]

On a small block oil filter 90* filter adaptor, there is a 3/8 pipe plug. Is that oil IN to the filter or oil IN to the block from the filter? Does the oil enter the filter from the threaded hole or the base of the filter? Lubrication schematic is not clear enough to see and I dont have an old block around to check.
Thanks in advance

 

[dustertogo]

The oil enters the filter through the base and returns to the engine through the center hole.