Buy a MB C107 450SLC

Hello! I am French, and I am currently driving a Golf IV TDI 101. I plan to sell it to enjoy a nice SLC. I am still a student, but I will work in a few months (and therefore finally earn money). An old Mercedes has always been my dream. I will see the SLC tomorrow, it should be in a very good condition. It is yellow, has insured 140,000kms, 1974, second hand, only some rust points. Leather, aluminum rims, climate, electric roof (sunroof The V8 runs perfectly, he told me, and he drives the car regularly. He demands 7,600€ for the thing. What do they think about it, is this price correct? Will the car not be too unreliable after the 35 years? Will I not have too many problems? What would a cavity seal cost? I don’t know about mechanics at all, but I am ready to learn. (Since I am French I make mistakes, but would be glad to be corrected to speak German better). Thank you!