Kyle, Very sorry to hear of the passing of your father. We had spoke a couple of times and emailed a couple of times about the Grand Sport. I am the current owner of your father's GS roadster. Your father had sold both the roaster and the coupe to Rick Costa in California. I believe he still has the coupe. Rick sold the roaster to the gentleman I bought it from in about 2007. I have done a complete restoration since my acquisition in June of 2010. You can see some of the pictures in my photos and avatar.
I am in the Dallas/Ft. Worth, Tx area and would be happy to share some of the history I know of the car and any further information you or your mother have.
Respectfully,
Ed Haven