[unruhjonny]

Guess work aside, I really believe that it would be hard to make a strong argument for the early articles and late articles both having the same Trans Am;

These cars debuted in February 1970, and presumably the February/March print date magazine articles were done with pre-production cars built in January or maybe earlier (the press should have seen them prior to the official launch).
Most articles state that the RAIII is the top option - some say "top option at this time";
Yet the Super Stock article irrefutably shows a RAIV car - we all know that the production RAIV cars were all July build date cars - so if the pre-production RAIV Trans Am was replaced with a production car -which was probably tested in April or May for the June articles, that puts it clearly in the time frame of RAIV being off the table for '70 Firebirds.

Then there are the interior pictures that show differences between the Feb/March and June Trans Am's.

I agree that you could have a drastic swing in drivers based on their skill;
I also will agree that a RAIII M21 car should be able to muster e/t's better than mid-fourteens...