Searching for my dad's Black 68 Road Runner

Hello Moparts I'm trying to find my Dad's 1968 Road Runner he traded in 2005 at the fall Auburn Auto Auction to a gentleman from the Detroit, Michigan area who was retired from GM. This is the Typical story often heard ...My father and I build this car together and he passed away in 2018 and I would like to get it back for sentimental reasons. The car when sold had a 472 stroker motor, 727 Trans and a narrowed Dana 60. The car had several custom features like an exposed trunk mounted 20 gal aluminum fuel cell, oil cooler mounted where the Battery tray originally was, white gauge cluster, custom center console with Hurst aluminum pistol grip shifter and GTX bucket seats. The Vin number is RM21H8A195707. Any help will be greatly appreciated

UPDATE: I was able to locate the previous owners wife from 2005, the husband passed away in 2010 and they lived in Battle Creek, Michigan, she titled the car in her name in 2016. I spoke with her on the phone and all she could remember is that she used a car dealer/ broker in the Battle Creek Michigan area to sell the car and that it sold pretty quick. She didn't not remember the name of the shop she used.

You and your dad did a great job on the RR.

Big attraction locally is in Hickory Corners, MI - Gilmore Museum. Mopars at The Red Barn. This year held July 24. Worth the drive to see the show any maybe find your car.

I hope you get it back.