I'm not Dano, but I wrecked a car in part because I installed helper springs.
What I learned the hard way was that stiffening the rear, when there is no additional weight back there, is a setup for the rear to fishtail back and forth at the worst possible time. In my case it was an off-ramp to on-ramp with a slight downhill. There's generally no recovering from that. The rear swings back and forth until the car spins around...
That's what's meant by a suspension that has a tendency to 'oversteer'
With 27 K miles, but that someone put Konis on, its hard to guess what you got there.
Nothing wrong with a fairly flat spring. That's what Chrysler wanted.
Exception is for drag racing, where arch can be made to help forward bite (with sticky enough tires).
Chrysler explains why here:
Extra-Duty Options (Session 253) from the Master Technician's Service Conference
If you want to make a general improvement in handling, if it doesn't have a front sway bar, adding one is the most noticible improvement that can be made. It was a factory option and sometimes available used when people junk cars or install a larger diameter bar.
