The original shipping bill for your car will show the color on the machine as it left Modena. If the first owner wanted a particular car but needed it to be a different color, it was very likely at the buyers' expense and done by a local contractor to the selling dealer. I doubt if any record of repaint was kept beyond the original Bill of Sale; to Ford and the dealers, they were just cars.
I once did a survey in Nor-Cal on Pantera colors back in '81: at that time on some 50 cars, half were red, 35% were black and the rest were yellow or a rainbow of other colors. The least popular were the two shades of green. Results (or tastes) have apparently not changed much in 40 years.