Looking into upgrading rear suspension

I built that same motor for a 63 valiant convertable of mine. I have a LD4B with 68 340 manifolds and a holley 670 street avenger. I only have a 2800 stahl with 3.23 and I ran 13:95 spinning like qrazy so that should be no problem. As far as the springs I have espo on mine and love the stance and ride. I have s.s. on my cuda and hate the ride on the street. They make the car very bouncey going down the road.