Start body work from the back or from the floor?

Hi!!

It has been a long time since I touched this car but I plan to get started on it again.

This was where I left off on the car...
http://www.forabodiesonly.com/mopar/showthread.php?t=173729

I'd like to know if starting with the floor pan or starting in the back such as the trunk pans would be the place to begin. The last thing I did was refitting the doors to ensure they were square and they are.

The odd thing is when the car sits on 4 stands. It doesn't. It sits on 3 but taking a level to the car shows it sitting square. Floor appears level... just don't understand it. Perhaps I need to move the stands to a differnent location? Any 'best' location on the frame rails?

I have AMD to replace most of the rear.