I recently took the body off my 54 panel. It was very easy just to remove those 10 (I think) bolts and lift it up. My floor was pretty good so I did not have to remove it or replace any wood. The floor wood is attached to cross members that are attached to the body, not the frame. It seems to me that it would be a lot easier to remove the floor after the body is off the frame so you don't have frame parts in the way. Good luck.
Off the subject... I saw a 50's something panel express being towed today, presumably to to be restored. It was in good shape and very exciting to see.
