I could be wrong but wasn't the ball stud Hemi a planned engine for across the board passenger cars to replace the expensive to build double rocker arms of the 426. Similar to a BB chevy design with canted valves. I believe I read something like that decades ago. Sorry if it is mentioned in the pictured literature already I couldn't make it out on my screen. One of them designed to late to be needed for production type motors if I recall. From the fuel embargo days.