Mr./Ms. 76. Welcome aboard. Oh golly, drains...To the best of my poor memory the drain on the starboard motor is inboard between the forward end of the starter motor and the oil pressure switch right on the block. Should be staring you in the face. Can't remember if the port engine is the same (on the starter motor side) or if the drain is mirrored inboard.
You'll have to drain the heat exchanger and I think the exhaust manifold as well (not sure about the exhaust manifold).