1991Swiss Testarossa with US engine?

Hi i'm looking at a 1991 Euro Spec Testarossa from Switzerland .......The Vin corresponds with Switzerland but is has an F113AO40 engine in it.......The Swiss model should have the F113AO46 without catalyst or the F113BO40 with catalyst in it according to what i read........Does this mean the engine has been replaced and if so how much less is the car worth because of it........It runs great but has no service records either