Unless you can get in a position to where you can drive the block of wood upwards. Also a lever out of wood as suggested by Achipmunk, stuck in one of the exhaust/intake ports and a good yank up on it. Those are the 2 best ways, IF YOU HAVE ALL BOLTS OUT!! That has usually been my problem on lots of things: One bolt still in somewhere.
I don't think I would like using a hoist on the manifold, it would be easy to crack or worp it.
