Why don't you offer the cougar to the lady straight across for the truck? Tell her what you believe it's worth, leave out what you paid. Personally I think the 67-68 cougars are cool as hell and I cant believe you cant find a buyer for it. Try this website,
http://www.racingjunk.com/post_ad?aid=32872 you can place ads there for free without photos and it doesn't have to be a race car. tens of thousands of guys check that website daily. I placed a ski boat on there and got lots of emails and a few calls.