AC compressor can stay on (I just removed the intake on my 86). Gasket sets don't even seem to come with the rear gasket; it's expected that you use Permatex. Same with the front of the intake. Also, make sure you get ALL the old Permatex from around the back. It'll leak again otherwise. I used a gasket removal spray.
Use a small pry bar to remove the fuel rails, GENTLY. If you've got the time, now's a good chance to get them cleaned and re-ringed...
You can use a larger pry bar between the cast-in lug on the back of the block and the manifold itself to pry it off. It'll stick...
It's also easier to loosen as many of the runner bolts as you can before trying to remove the plenum; there are plastic pins holding the plenum->runner gaskets in place and loosening the bottom of the runners lets them move enough to ease the gaskets out. I also tapped with a rubber mallet to loosen the plenum. Also, some of the runner bolts are loosened from the OPPOSITE side of the engine.
And please, PLEASE triple-check that you got all the manifold bolts out before trying to pry it off. A couple are somewhat hidden and a new manifold is expensive... though also a good excuse to get a performance one

.
If you've got a late 86, careful not to scrape gouges in the aluminum heads when cleaning gasket off the block... and the runners WILL dent if you drop them...
Oh, and I found the best thing to use for storing bolts is an egg carton. Cheap, oil-proof, and compartmented.
Good luck... it's not as hard as I make it out to be.
[RICHR]