I'm currently swapping LT1 heads on my engine. The heads have already been welded and I've already drilled and tapped the front of the head for coolant routing. My question is, when I lay the head gasket on the head. There are four holes that are not present on the LT1 head. The two big ones marked in red and the two little ones right next to them. If I remember correctly, in the big thread on the swap I didn't see the big holes drilled in the pics of his heads only the little ones. These big holes (circled ones) seem to go from the valve spring rocker area into the lifter valley. Are they necessary?