Got the trunk floor pan into place today and kept it in one piece.
I learned a few things along the way and hope they might help some others.
First, you have to drill out all the spot welds along the lower portion and ends of the tail panel. You will be bending this out almost horizontal before your done.
Second, you will need to raise the rear of the car high enough to get the front edge of the floor pan under the tail panel. I was able to do this on my jack stands by raising them about 6".
Next, you want to make sure you have all your spot weld holes drilled, especially where the pan and trunk floor extensions weld up. You will notice in this first picture how far I got before I realized I hadn't drilled the holes yet. Fortunately I was able to drill them with the panel in this position. Notice I clamped it into place while drilling.
I used a couple of small pieces of 2x4 to hold the tail panel open but found they only worked to get the above position. From here I would work one side at a time by bending the tail panel with one hand while pushing the floor pan up an inch or two. Eventually I got to this stage where the front edge cleared the rear deck panel supports and is resting against the trunk lid hinge brackets.
From here on out, I would push on the pan with my legs while lifting the tail panel with my hands high enough to let the panel move forward.
Eventually I got it into place and started realizing how many spot welds were staring back at me. LOL
Here's how far the tail panel was bent.
I carefully bent it back down and then using vise grips and a body hammer got it back into fairly good shape. I'll work on it more when I start welding everything into place.