Cooling system questions

[Don-T]

I have the heads from my 6.2 at the machine shop getting fixed. they are warped 0.004". The shop thinks the engine likely was overheated to some extent. I don't know enough about these engines to diagnose the cooling system but I bet people here do. I did notice both the block and heads have six coolant holes between the center cylinders where the heads are warped while the head gaskets appear to not have passages in the same locations. Is it normal to block the coolant flow to the heads in the center like that to force it to the rear of the engine? Is this good or bad? Should the new head gaskets have some sort of holes to allow coolant flow from the block to the head in the center, or just rely on coolant flow from front to back in the block and back to front in the heads?