Because I saw it in the garage of the owner of 1150, around 100 meters away from the wreck of 1150, a few years ago.......
The owner would not let me touch the car, go near it, open the engine compartment, thus no way to record the serial number. Also, no photography.
They wanted to sell me the 1150 car - as a restoration project with a price more suited to a pretty good project car.
This car was at that time definitely not for sale. Though I did also see the pile of Nardi engine parts which apparently came from 1150, lying in the corner, well-preserved. I believe the intention was to transplant those parts onto the 6th series, as the 1150 had a 3rd series 2500cc engine (as you already know).