If i were you i would rebuild the axle (king pins & bushings, Tie rod ends, etc.) Add new tires and alinement. It should be fine - but if not then install new shocks - Having your springs rebuilt is a lot cheeper (some times) then buying new. Look in your yellow pages under truck springs. Big truck spring shops can rebuild your old springs to factory specs. Your straight axle once in good condition will perform just fine.
Regards, HonestFrank