The car is interesting indeed.
Did it change ownership in the last years?
Last recorded owner of 00125 was Mr. Hayashi in Japan. Maybe he still ownes it and he himself brought the car into the Pebble Beach condition?
The colours fit to the paint that was used by Bonnier in the last races with this car.
It is also interesting that engine #00507 is mounted, as this photo shows: http://www.ultimatecarpage.com/pic.php?imagenum=5&carnum=3362
First engine should have been #00505. Following the numbers of the factory, 00507 was originally in the Spider that won the Merano race with Fangio. It must have been changed during the car was still owned by the factory.
Next logical question is what engine is in the 6C3000 CM Spider in the Alfa museum???
Btw, for those who are interested in numbers, here is a photo of engine #00521 that I recently took in the museum in Arese.