It might have been a little easier if you could have removed the studs, as well as the nuts. I know there isn't much room to work back there, as i just replaced my manifold gaskets. Another thing that could have been done, although the info might not be very useful now, is loosening the nuts that at...

there are 8 nuts holding the manifold to the block. Unbolt them, remove the studs (carefully, you do not want to snap one), and the manifold will be free of the engine.