I'm sure your fronk end just needs to be rebuilt. The king pins get sloppy and need new bushings etc... Fitting V8 bushings will help firm everything and last a lot longer then the original 2 piece rubber ones.
Check wheel bearing/hubs/tie rod ends/sway bar bushings and steering shart u-joint.
As for fiberglass leaf springs.. I have them on my 1980 V8 Conversion. It greatly improves the ride... I use tube shocks vs. the OE ones. I also have traction bars fitted to control spring wind up.
After fitting the stiffer ft shock valves, it's really a great riding car. Very smooth and comfortable.