Caltrac’s and high rpm doesn’t mix

My 68 fastback has the same set up on it , and it didnt do the bouncing thing, only had 10'' wide drag radials on , virtually no front end lift , it went straight and didnt bounce at all , altho it was slipping the tires. Knew a guy with ladder bars , his duster would run low 9`s w/ ladder bars , and threy didnt change the front spring segment length either----------??