Welcome Sunit!
I read your first post but having nothing definitive to say about the history of your car I kept quiet. There are some very knowledgeable BB'ers with respect to Alfa history and with pictures posted you will more likely get the help you desire or at least more educated speculation than I will now offer.
Regarding a modified nose, I will guess that it probably (if raced, almost certainly) suffered an accident in its early life and, as seemed to happen back then, if the accident was bad it was cheaper to have the nose rebuilt from scratch than repaired to original. The car was probably modified to some whim of Dr. Bertozzi, perhaps even based on seeing the car you are refering to from the other thread. The story is something along the lines of the cars that are collectively refered to as SVZ's.
Alfa Romeo Sprint Speciale