HeHe I suffered a water leak similar to yours. Had starter changed and it turned out to be a bolt had been missed out when the guy put it back together. Follow the dipstick tube down and you'll see a bracket that hold the tube to the block. This bracket is held to the block with a bolt which is an upper oil cooler bolt. Top edge of oil cooler seems to be on the joint between the block and head.
Also look at this picture of the head and see the core plugs at the side and slightly below the inlet ports.
Jim