buyer/seller integrity question

Rule #1 when dealing with a sale. When the words lawyer, court and sue come out of the their mouth, my mouth goes shut.
Cut off all contact at this point. If he does sue, he's going to have to do it in the county you live in. It'll get in front of a judge who'll see a sale of a 60 year old car and his list of problems and either toss it or side with you.
Most of all, cut off all contact.