The last picture you post about the chassis repaired made me compare with my BT16 (AM57). I mean that the roll hoop seems to be very similar and wheels to be at the same width.
In my case it is the opposite, I know the story from now to approximately the early 80's/late 70's. The last known owner was leading a Citroen garage in Marseille, France (specialized in Panhard, and I know by some people that he had had switzerland customers). I supposed the car has been crashed because pedals are wrong fitting and the oil tank has moved to the back. It might be a coincidence!
Kind regards,