On certain combinations of cylinder heads, blocks, and rocker arm assemblies, there was a drilled head bolt in the center position. It's an easy modification, as the hole in the bolt only needs to be about 1/16" in diameter. Center drill the bolt to just above the threaded part, and cross drill a hole to intersect it. Another method is to grind a narrow groove in the head bolt threads to let the oil pass through. The factory bolt has a slot across the head that resembles a big straight slot screw.
Quit obsessing about that last pushrod, unless you're willing to remove the cylinder head to get it out. That's the only way it's going to happen.
Jerry
