9.9hp Merc (1999) Powerhead removal

[derfxa]

I'm getting oil/water mix from carb lower vacuum tubes that's fouling the engine. I think (hope) it's a powerhead gasket failure. I'm planning to remove powerhead(PH) (basically 6 bolts and loosen shifter linkage) to replace the two gaskets underneath PH. Do I need to drop the lower unit to remove the PH or can I leave it in place? And while PH is off is there anything else I should replace?

Thanks!