I've been turnin wrenchs for goin on 35 years and I've never seen any repair manuals that mention the location of oil galley plugs, although thru the machining process all engines have them, Any machine shop worth their salt removes all of these plugs for hot tanking, and usually hands ya a box full of plugs when ya pick up the block leaving you to figure out where they go, Don't sweat it guys ya aint the first or the last guy to ever leave one out, ( My Old Man always said a smart guys nuthin more than a dumb S.O.B. with a lot of experiance) And as Proz said even though it's been tanked every thing should be at least blown out,
I always use Hot soapy water, my engine brush set and compressed air to clean everything out before assembly, and always,always prime the oil system fore ya fire up a fresh engine.....