Could still do it but it wouldn't be easy. Have to have the blessing of NASCAR and that would require a lot of time and money. Might be cheaper to build their own and hire a driver. Only problem is NASCAR really wouldn't let them build their "own". They would let them build the same car. They control everything and it all revolves around controlling the cash.That's why technical set ups, tire and fuel management and pit stops have become so crucial. Right on the mark about the changes starting in the mid to late 70's. That's the time frame I was around it. Champion spark plugs had been around since day one. They would give you plugs and technical help in exchange for you putting a Champion sticker on the front fender just in front of the doors (cowl area). Sometime around 1976ish NASCAR said they would have to start paying big money to have the stickers on the cars. They bailed. Manufacturers to some extent have done the same. Today they just pay money to have their name on it. I laugh my ass off when the announcers say "there are Chevrolets in the top four spots". They are all the same freaking car. Nothing remotely stock about stock car racing anymore.