DJ
Hate to ask the obvous, but did you remove the crossmember? You need a jack under the deep part of the oil pan so you can let the back of the engine down, AFTER removing the distributor cap and loosening the fan shroud.
The tranny should come right out if everything is ready, this is not a problem area.
>>HOW do you massage the floor pan??? TIA
With a big hammer, how else? But, the TH400 was a factory option in Chevelles, your floor pan shouldn't need any massaging. What year is your car?
Here's the big gotcha, tranny cooler lines. It's often extremely difficult to install them after the tranny is in and all bolted up. I believe 400 lines are different from 350 lines enough so that your old lines won't work. You might might to check into this some. Maybe somebody who's done this swap recently can give clue here.
Tom