I read your posting yesterday, but didn't have the time right then to sit down and type it all out.
A 70 Coronet R/T is most certainly worth digging it out. But trying to give a decent reasonable estimate of value without seeing pics of it's condition is like trying to shoot darts in the dark. You might get close, you might not.
A 70 R/T in "parts car" condition, with ALL components there, might be worth a couple thousand depending on options, color, etc, etc....
A running driving car is probably worth a little more. If it's in any kind of "survivor" condition with most of it's original paint that can be cleaned and buffed to make decent, you MIGHT be looking at $5000-$10,000, maybe more but again it all depends......
But everything is subjective with a written description of condition.
Pics are a lot better.
Personal first hand inspection is the best.