The hole in the boat isn’t big enough for the saildrive to be lowered through the hull. I’m going from memory as is was a couple of years ago. While draining the oil from the gerabox we disconnected all the bits from the engine eg. fuel lines throttle etc, we then de-coupled the saildrive from the engine. We then moved the whole engine as far forward as we could, not the couple of inches suggested in the manual. We then removed the drive at the bottom of the saildrive (it will not fit through the hole if you don’t) You then remove all the bolts from the drive, then lift the saildrive out, swearing helps at this point. I think we pulled the drive through the cabin. Once on the deck you replace the gaiter using a replacement kit which should have all the instructions. Then you just put everything back. Sounds simple which it is but like I said in an earlier post the problems you face are lack of space.
Hope this helps