I never knew Toronado had a torsion bar front suspension, but, since it does, you will find and adjust for same where there is a lever arm and adjustable screw at one end or the other of the bar. You can adjust the ride height there.
Torsion bars are , quite simply, uncoiled coil springs and wear out too, but they do have the advantage of being adjustable up to a point.
Leave the shocks you have on there, adjust the front suspension, replace the rear coils and see how things are then.
It has to get better, I think. You may be able to buy new bars for the front from GM but that I don't know for sure about.