It's all about the condition. You'd want to find out how many stock parts it still has on it.
It's not the easiest thing to do... but if it has good tires, brakes, ignition parts and other wear out parts, I'd say it's probably worth about 500 to 1000. I definetely wouldn't pay more than that.
I'd say you can forget about tuning this car to make it fast, but I can tell you that my 82 was one of the best handling cars I've ever driven. Absolutely no unwanted pitch or roll in the cornering. It's brakes will stop it pretty quick and it will be great on gas, provided it's running right and stuff.
You just have to learn all the little tricks to keep it up to speed. :driving: