Look at the valley, there is a ~1/2"-wide channel cast in there--one on each bank--going from the cam tunnel up to the deck. The oil feed hole for the LA rockers will start on the deck where that channel casting ends. I don't have a pic but the hole is between some coolant passages IIRC, on the top part of the deck between the front two cylinders on one bank and the back two on the other.
