The head gasket should match the holes in the head and the block. On some earlier years, there were holes in the head and the gasket that were dead ended at the block surfaces.
If the block has not been cleaned professionally in a tank, the petcock area is probably plugged. This doesn't normally present a problem. Your coolant surge may be the result of an air bubble. Also if the thermostat is stuck, coolant will come out the overflow as the motor warms. You could try running it without the thermostat first, to see if all works well without it.
