68 Dart GT suspension upgrade recommendations - best bang for the buck

I bought a 68 Dart convertible. Originally a 275 car now with a 360. Looking for a list of the 'must do' handling upgrades. I just did the pump it down procedure and that made a noticeable difference in handling. It has air shocks in the rear and gabriel shocks up front (both new). Ride feels bouncy over bumps and the car sways a bit after. I was considering Bilstiens as I put those on my Grand National and it was night an day. What have you done that made an immediate improvement?