Get the exhaust off. Soak it in WD40 for days, then tackle. Is going to be the worst bit.

Agreed with Scotty, wedge the read wheel and with a breaker bar and hammer, shock the sprocket nut off. If you can VERY carefully apply heat to the nut, it will break any thread lock in there.

As to the engine, I imagine that it is going to be the better part of 100kg. You'll need two or three people to get it out the bike safely.