You would probably need to go to a much newer axle housing and a considerably higher gear (Maybe 4.56 or a bit higher) to get that kind of highway speed without making your 383 sound like a bumblebee on steroids. You'll also need to do a major upgrade on brakes, ditto on steering, before those speeds would be safe. These trucks were intended for top speeds in the 50-55 MPH range. Getting 50% more road speed is an exercise in irresponsibility unless the handling and braking is upgraded as well.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!