If you have an Oldsmobile engine, you NEED to get Joe Mondello's tech manual, at a bare minimum. Joe is Mr. Oldsmobile, and knows more about them than anyone else. The oiling problem is that Olds engines tend to hold oil in the top of the engine, and not let it drain back quickly enough. The easiest fix is to get a set of restricted push rods. This does not require removing the engine from the boat. More safeguards include a larger capacity oil pan, and restricting the oil passages above the main bearings. Restricting these passages requires the engine to be out of the boat, and dis-assembled. Also, you can enlarge and smooth the drain-back passages in the heads and block.
Like I said at first, get Mondello's manual, and his catalog too. It has invaluable info. for Olds lovers.
SteveM.