On the body, in 1975, the M/P rules were clear on what little modification were allowed and those mods were pretty much restricted for motor /trans install, tire clearance and safty. Rules were in place to prevent Pro Stock cars of that era with altered wheelbases, tube chassis and aluminum interior /components from showing up to compete in this class. The only pushing of the rules I am aware of is the removal of the guardrails in the doors and liteweight aluminum replacement for the heavy front bumper shocks (sprayed with metal in the paint so if checked with a magnet, would apper to be steel). The car was fast.....no sense in pushing it only to get labeled a cheater and get disqualified AFTER a win. It was the factory race car in the sportsman ranks and under extreme scrutiny by tech and fellow racers.
Amazingly, this race car is very similar to the early (1970) Pro Stock cars. When Pro Stock began, they did not even tub the cars.
I find it interesting how the front wheelbase is moved forward approximately 1" for the large front tires using non modified factory components....... early A body spindles swapped side for side.