These cars have speed sensitive power steering? (AKA variable rate power assist)

[C10CoryM]

Hey guys, I am building a little rod that will use C4 front suspension. I just need to know if these cars use variable rate power steering. IE the faster you go the harder it gets to turn the wheel. If so, do you happen to know if it works off the vehicle speed sensor or like the new GM, off a steering wheel speed sensor? If not I will have the reduce the power assist to minimal with a relief valve or similar. Full power steering at race speed with a 90" wheelbase would not be good. Id just as soon have a manual rack and lose the weight but Id also like to not spend a few grand on an aftermarket rack . Thanks for the info.
CoryM