Buying an old car is done because it pulls at your heart strings not because of its market value or future gains. One cannot establish a market value for such cars as one can for modern ones. For example an old car can be for $10,000 and yet for the same car, if previously owned by an important personality, can put the price at $100,000! Regarding the Impala, you can do your homework and estimate how much money you will have to spend to get to the level of perfection you desire and then make him a fair offer. Be warned owning and old car is a commitment not suitable to all. It is EXPENSIVE to restore them properly. When they break, they are hard to fix. Not any mechanic will accept them. The ones that do are crocked and tell you tall tales to make a big invoice. If you do decide to step into the world of old cars, there is much joy in driving around in them and the looks of admiration from other road users.
Finding parts for this car in Islamabad will be next to impossible. Your best bet will be Perfect Motors in Karachi. Keep in mind that parts from Perfect Motors may not be 100% the right ones but may be close enough. Depending on the level of perfection you desire, your best bet will be to import parts. In the USA parts are in plentiful supply and quite cheap compared to, say, an old European car. The business of importing parts is easy. The hard part is paying for them. Custom duty is calculated at about 80% or so of the landed cost. The landed cost is the cost of the part plus the cost of shipping. So you can imagine you end up paying twice the price in rupees of what the part costs in US.
Good luck with whatever you decide
