CWL

Our local sailing club's '99 Yamaha F80 developed an oil leak this summer. It would leak oil all over the inside of the boat's transom when the motor was tilted out of the water. It was difficult to determine where the oil was coming from as there didn't appear to be any visual oil leaks inside the cowl. I consulted some local Yam techs and they told me that is was common for the oil pump seals to leak on the early F80s and F100s. From my description, we concluded that this was likely the problem with this F80.
So, I removed the powerhead in order to repair the leak. The seal on top of the oil pump doesn't appear to be leaking, but oil did come out with the driveshaft when I later removed the gear case. It does appear that the powerhead's base gasket may have been leaking, but I couldn't see any breaks in the gasket. I'm, of course, going replace the powerhead base gasket, all the oil pump seals and the lower crank seal on the engine block. Hopefully this will solve the leak as it is difficult to determine where the leak is coming from. Here are some pics: http://s9.photobucket.com/albums/a84...0Yamaha%20F80/
One big question I have that I can't seem to get a definite answer on is if I should replace the oil pump itself or not. I know there's an updated part, but is it necessary to replace as it appears fine other then a possibly leaking seal? Seems like a lot of money to spend just to get an updated part that may or may not be necessary. I want to replace everything that should be replaced, but not go overboard.
Also, the motor developed an odd whirling noise that changed with RPM. The Yam techs advised me that it was likely the driveshaft bushing. That's why I removed the gearcase. I'm also going to replace the water pump impeller while I'm there.
Any thoughts, suggestions, advise?

- Chris