Going to cost a lot of money to restore, $50,000 or more is not out of the question. You are going to have to buy a lot of body, trim and mechianical parts (likely little can be saved) and th labor will cost a lot of money to be done right. Expect to pay over $10,000 just for body work. Engine/tran/axle coudl set you back another $10-15g.
I showed these photos to a very good body man (restored many cars in his 20 yrs) here and he said, he would not touch the car without a large deposit on parts and he would need a blank check, you pay him whatever he wants when he wants or he stops work. Evn then he says he would quote you a high price for labor and hope you went somewhere else. He recently did a 1969 Z28 Camaro that was a rust free original paint body and it cost the owner $20,000 incl. all parts and materials. Car is perfect down to the exact detail. He does such good work he is booked 2-3 yrs in advance. His motto apears to be, "if you have to ask me how much, you can't afford my work".
If you feel you can do the work yourself, think again. Unless you have $10,000 in tools, a shop and a lot of cash, it will be a losing proposition. Amature restorations don't bring high $$, too much of a gamble for the buyer as there is no reputation of the restorer to trust the work was done right.
Thats my opinion..
I would sell it for a profit and look for something better.
What would overhauling do with it? Bet they would be looking for another car?