1973 Cougar Convertible for 600€

Hello, a colleague of mine knows someone who wants to sell Mercury Cougar Convertible in 1973. He has been standing dry in the garage for 12 years (!!!). I can’t say anything about the exact condition, since I have not seen him yet. He also has some new chrome parts with him. The engine is en 351 Cleveland. Are 600€ justified for so much, and if so in what condition does the car have to be for this? What makes me care are actually the 12 years in the the part already stands. And I also want to start the engine net so easily, because the oil after the time is certainly thick-fledged already. And so en Convertible Top also gets cracked over time. Does anyone already have experience with such a Cougar? Greeting Patrick