A lot like my dad's story. He special ordered his 67 Dart GT 273 Convertible, he wanted a V8 but also economy so he went with 2bbl. No PS, PB, or AC. The 67 GTS was not available yet any way.
He special ordered it, kept every recept and a log book. It stayed in the family as it was his daily driver for 25 years racking up 300,000 miles. He was forced to retire from his management job at McDonald Douglas at which point the car was driven infrequently, about 1000 miles a year, for the next 30 years. He passed away in 2017 and not I am enjoying it.
Your mom's car is a great story and the restoration of it is awesome.