Need advice

My wife and I are looking at buying a 1985 Sovereign. Kind of a barn find, all original, been stored inside its whole life, even the tires are original. I am told that everything works nothing leaks. It has only been used a hand full of times in its life. what should I be worried about with the age of everything is it all going to need replacing soon since its hardly been used will it last for a long time? Just dont know enough. Any advice would be great. any ideas of a value of such a find? Thanks