One guy here did drop in with the rear header on. It looked like a real pain in the neck as they had to tilt the engine and do all sorts of stuff. I personally lay the rear header piece on the trans and then bolt up as it's coming in. Works great overall.
Another option you could do is to unbolt the rear manifold from the head. Pull the exhaust back slightly at the tips and you should be able to take the motor up and out w/o any issues. Then with it out of the way..get in there and have some room to fight the battle, or use your other manifold and just cut the bolt to get the DP.
