Below is the diagram for how the oil pipe threads through the 216 engine block. I included a few pictures to help you sort things out. The threads are 1/8" NPT and are sweated in place. This is now the oil gets from the bottom end to the valve rocker assembly. The line threads through the water jacket and up through a hole in the head and connects at the rocker assembly. You want to make sure those two fittings on the block are leak-proof because coolant will leak out otherwise.