Its pretty easy. I rebuilt a craigslist engine over a week or so, then put it in within 3 days maybe, counting lots of perfectionism cleaning things. The engine drops out from under the frame, makes it much simpler. You can actually remove the whole power unit by lifting the frame up off of the engine, transmission, and final drive.
Take a look at the factory manual for the factory description, and check out the haynes and others for more info.
Its a lot easier than the KZ900 I would think.