I would tell you that in the papers of the vehicle he sets displacement and power, assuming you do not have them. Pill yourself the chassis number or motor number and approach the Chevrolet house. Or do I know if in your country it happens but you are going through normal give the name of the owner and they tell you this person has in his name a chevrolet tbi engine ??? power ??? color ???. <- With the car registration it also works.
From what you say is a monopunto block, you can ask that of the spare if there is separation between the screws that anchor the collector.
That car has an Opel engine and are the same to the sight