Don,
The article in Hot Rod was only about the Chevy engines and didn't really say where they have their big facility. It seems that Chevy only furnishes a rough block and rough head castings and they do the rest. They would build the engines from scratch but NASCAR insists on something coming from the manufacturers. Also wouldn't let out the horsepower figures but it is over 850 and they are setting them up to run 9400 RPM. They make everything in shop including cams & etc. It is an interesting article.
Ron
