Larry good to hear you made a decision. I have a statement around 1972 6BBL Road Runners from research I have done through out the years hunting for one of the two 72 4406BBL Road Runner.
I have seen reference to your Road Runner in this and other treads being referred to as a RR/GTX. Correct me if I am wrong, you had said the car never seemed to have evidence of GTX emblems on it. Being it is a 6BBL V-Code it would have to be a Road Runner and not a Road Runner / GTX. The GTX option in 72 referred to a 440 4BBL engine package and not a 440 6BBL engine. Good luck with your restoration keep us posted on progress. Hope to see it soon.
I have a question, when restoring your car do you plan to restore it as a Road Runner or RR/GTX?