Hi Russ,
The Sprint cars I'm familiar with were between 83 and 90 inch wheelbase open wheel cars that usually used a pair of airfoils. The Gambler chassis design was exceptionally rigid and the suspension exceptionally compliant. While not having built sprint cars from scratch - I've worked on them.
The Latemodels used 104 inch wheelbase closed wheel and usually did not use airfoils.
Yes the late models were built very lightweight and they had to be. Yes the chassis were designed to be an extension of the suspension of the car and needed to be in order to maintain control.
Were we doing it all wrong? Maybe - but we helped win a number of championships doing it that way.
Still there is more to be learned.
Examine the failure points of existing chassis as they hold many secrets..