Head Gasket question on 340

Ready to put heads on my 72 340 engine, and had question about gasket and fit to this engine. The Victor gasket set is for 72 340 and head gasket is CA-1432-G. Anyway the picture shows my question that the large water port on front of engine is blocked by gasket and open at rear. But the intake manifold has no water port at rear for that open hole. The locating dowels line up to gasket in that position. I checked it to the old gasket and it is identical. So why is the front water hole blocked by gasket?