I found if the tail pipe is unbolted from the exhaust manifold it helps two things.
1. removal of the starter. 2. allowing the rear of the tranny to easily fall below the cross-member where the drive shaft enters the frame.
This may or may not be an issue without the overdrive. I am not sure.
Just watch the oil filler tube at the top of the head cover. It can touch the fire wall. I would remove this as well, for piece of mind, when the engine starts to float back once the tranny mount is removed.
Have a jack under the engine and another under the tranny.
dgb