I have an opportunity to buy a supposed 1968 Z28 for $4000.00. The motor is not original but the car is in good condition. What do you think the value is? Is $4000.00 to much for it?

I'd say $4K is a pretty good price for a rust free body with a good pedigree. Maybe you can find a correct, dated motor. Good basis for a resto project, but don't plan your retirement around it.