Plum Mist is a fairly rare color, so that helps. Being an original 400 car with the original motor helps, tranny not as big of a deal, but original numbers on all always helps. Convertible always a Plus. The other options are good ones as well. With out seeing the condition, kind of hard to say.

But I would have to guess it could be in the $15k-$18K range in today's pricing depending on why it's not running and over all condition and what may need to be done to it. The better the condition (no rust, never been hit paint that will come back etc The stronger the price obviously... The more work it needs, the closer to the $10K side it could go...

With an upcoming election year things fluctuate greatly as people are uncertain of which way things will go. So if you are serious about selling, starting now and into the spring is the best time to sell before politics ruin yet something else! Lol! If you can get it running, that would help the value tremendously...

Again, this is all just speculation guessing that it's in good to very good condition... We've all seen something that should be scrapped where people are asking $20k for it? It all depends on what it's worth to you, and then you just need one other person who sees that value in it as well...

Good luck (but I hope you keep it and fix it up to enjoy for many more years!)