It sounds like you really want to drive it at speeds above 45 MPH. One thing you can do is to (assuming you have a 3100) upgrade to open drive and swap your rear for a modern rear. That will involve mostly spring perch and drive shaft modifications. That will improve your speed and if you want to go further you will already have the rear end in place.
Some of us like the old truck feel and ride and looks and keep her stock, some of us like the look of the old truck and will only change the ride & feel (comfort), and some of us like to make body changes (chop, channel, etc.). You make the choice of what you want your truck to finally look and ride like.
Good luck with your decision.
