Wow your right can't find anything about Jr dragster plans on the net. Get your camera and a pocket size tape and head to the races this weekend, pick up a rule book, take pictures and measure what ever them guys will let ya. I'd bet most of those folks will tell ya a lot about em and let ya measure. then go home and design the thing,If ya got the ability to build your own chassis then ya oughta be able to draw one up with your head loaded with enough info..
I gotta a buddy that builds his own , goes out and smokes them store bought cars,sells it for a profit and does it over ..
I'll check and see if he's got any kinda blueprints,But knowing this guy the only plans are in his head & in chalk on the shop floor............