I'm in the process of putting the top half together on my on center stage 2 (153) block. I noted that when I place the heads (1st. gen. GN1s) on the block without the head gasket, what appear to be steam holes on the outboard portion of each cylinder are exposed (total of six holes). I think that they are steam holes because they appear to lead into the water jacket. When I place the head (fel pro lockwires) gasket on the block, it covers the holes but the heads do not cover this portion. How do you plug these holes? Any assistance is appreciated. 
