The rocker stand oil galley is open to the headbolt. Pressurized oil is therefore on the head side of the head bolt. The head gaskets have embossing around the cylinder, water passages and oil passage, but not around the head bolt, so its easier for pressurized oil to leak out. I wish I had taken pictures. If you remove the rocker stand that is tied to the oil feed port in the head (between 5 and 7 say on the driver side), that stand will have a hole drilled to feed oil to the rocker shafts. The only two rocker stands that need, or should have the hole, are the two that line up with the oil feed holes in the block. On my stands, several had the oil feed holes. The bolts that hold the shafts have enlarged bores to pass the oil from the drilling into the shafts. Again, the other rocker stands had this too, so oil was able to pressurize these drilled passages. I think only way to understand what I am trying to explain is taking a look at the rocker stands. If the front stands have holes, then I would bet you are getting pressurized oil at the front head bolt, and since the head gasket isn't embossed around the head bolt, oil is being pushed out to the lock/head interface. I am just saying I had my engine apart three times before finding it. Once I blocked those passages in all but the required rocker stands, I had no issues.