I always thought that lawyers should work for 33% commission on everything. That way if you get convicted and get 10 years, the lawyer serves 3.33 years of your sentence and pays 33.3% of your fine.
But enough of the lawyerly hijacking. Mark I hope everything works out for you.
If I was you, I'd just keep the car and enjoy it. My grandfather once told me: The best revenge is living well.
You have the car, all he has are some old pieces of paper.
P.S. You are overlooking the logical fact that the original owner exists: that is indisputable pedigree evidence in and of itself! There are many undocumented cars out there that dont have any paper trail or people trail to corroborate their provenance. You have it.