Blocked off coolant port above serial number?

[Slowmotoring]

Just took of the head to replace the head gasket. When i got the head off i noticed a “pile” off gunk setting on the head gasket just above the serial number. The head has a coolant port in that location but the gasket and the block does not and it is visible in the block that the port was once there. Does anybody know the reason for this?