Coil springs

Just my $0.02

A prior owner swapped the rear in my '72 wagon to one out of a '74 coupe with a sway bar. It's no Miata, but it holds the line in freeway-speed turns a lot better than I would expect.

For coil springs, have you read these pages:

Ride is very subjective, so it's hard to say what you think is too stiff or soft.  I'd say you don't want a spring with less than 400 in/lbs unless you want a marshmellow soft ride.  The CVPI springs are probably the best performance spring upgrade for out cars, but they do ride fairly stiff. They are roughly 710 inlbs. Install those with a set of Addco sway bars and it will make a drastic difference in the handling.  Keep in mind Moog CVPI springs are no longer available.  However, other companies do offer equilvilents.  Look up 1999 Crown Victoria and select the police springs.  For instance MEVOTECH SMS80090 or LESJÖFORS 4127566.

See this rock auto link:

Other parts like Spohn rear control arms, Little Shop spherical bushings, tubular control arms all help too.  IMO, the biggest improvement comes from stiffer springs and decent sway bars.  These cars came from the factory with very soft springs and a low roll center, which is not a good combo for a good handling car.

FWIW, I run Moog CVPI springs, 160 in/lb rear springs, Biltstein shocks, addco sway bars, spherical strut rod bushings, and poly rear suspension bushings.  The car handles excellent with those upgrades.