Hi Wajid snd welcome to the club.
This model was actually a standard model but, as you could guess, was also a car that used a lot of fuel. At the time of its manufacture no-one realised that the Government were going to dramatically increase the price of petrol. When that happened Jaguar started to make a new cylinder head -- the AJ6 -- engine improvement made the car more popular and the V12 engine was abandoned.
The time this happened was when Jaguar was part of the British Leyland Motor Company controlled by the then Government, and it is a lengthy piece of writing that covers the situation. This would take me several hours to write. There are two books which give the position in detail, and I would recommend that you read them.
There is "Saving Jaguar" by Sir John Egan, and biased as I am, another book that is available if you look up "Transporterama " the online book shop. This book is called "Jaguar. The Cars and the People" and I spent two years writing it.
Your car is a classic and certainly one that is quite rare. It is certainly one of high value. I would definitely keep it.
There were not that many built and I could not find exactly how many, but it does seem to be exactly as the factory built it.
Regards,
Peter.