Very interesting that a 71/72 car would have the rear panel swapped out, that is actually the one thing I would also do if I was to execute a GT5S conversion on an early car, not doing so is an immediate give away, much like a LHD GT40.
I wonder if they executed the full late model interior and I for one would be interested to see the engine bay, who knows it may have magically acquired an Embo chassis in the transformation......