malibu43,
the bar you are refering too. it goes after the rear axle.. before the bumper. i know what you mean, i think you should look at it like this. anyting you can do to stiffin the frame from lateral forces applied against it, should be applied.. i too am going for a pro touring style of my 78 malibu.
i plan on purchasing air ride tech suspension, as pro touring site gave me really good feedback from it. there mucle bars setup.
then the fender braces from a monte carlo ss. and the front support i believe it comes of a caprice.. it bolts to the front frame horns, and meets up at the "skid plate" of the front end.. think of it, as many triangles to be applied to the vehicle, add them..
and drag racing vs autocross/ road racing is completly different as far as setups are concerend.. many have told me about a man named herb adams. he wrote a book for gm chassis handleing . and as far as i remember reading, he was very infulencial with gbodys..
im not garanteeing my information is 100%, because i too am still learning.. you should subscribe to pro-touring.com,
the guys on there are very informative.
good luck with your build brotha..