Diana,
Ill tell you what I would do if I was you, based on what I understand about your situation and what I know. You plan on keeping the car and are happy with it and will get the Holy Grail Title in Texas?
All good. Other than researching the history to a point, I would let sleeping dogs lie.
Titles are a big subject of debate. Each state is different. Georgia does not issue titles on a older car if you dont have one.
(That may change. There is legislation)
There are legitimate ways available to get one if you want to for your "Road Runner", I think.
Researching your car might turn something up. It might not. Time and death will cover a multitude of sins.
The car is going on 50. What can we expect to have happened?
Just to give you an example, I have a car with an older title. Not the original title, but old.
I consider it part of the cars history. It was signed over with notary to the person I bought the car from. I have a notarized bill of sale from that person.
I will not give Georgia the money they want to transfer the title. And I may or may not try and contact the person that retitled the car in 74.
Its a title.
What difference does it make?
The point is if there is no way to definitively identify your car and Texas will issue you a title, I think that is golden in the law.
You have a Certificate of Origin issued by the sovereign state of Texas.
It is a curiosity and relic.
Others may differ for sure, But thats my opinion.
It's just as likely you have a Frankencar as a complete stolen car.
Or both.