B body is a bit ambiguous; what year, body style, drive train etc?
I agree....The picture he has shows a '70 Coronet so I'll just figure that is the one.
THis car has been an ongoing development process. It handles quite well. I didn't do everything at once though. I've owned the car 20 years. I've tried different shocks, sway bars, torsion bars and tires.
First up, where and how you spend your money depends on what your overall goal is for the car.
A man that just wants to be able to drive it safely and have it respond well can get great results with a factory stock front end rebuild, a good set of shock absorbers and some good tires.
If you are looking for much more, it is going to get much more involved.
As stated, weight is an enemy. The lighter the car, the less mass that the suspension, brakes and steering have to work with.
The suspension works best when it has a rigid platform to work with. The addition of frame connectors is a great way to add stiffness. The added weight is worth it here. I have them along with home made torque boxes.
The stock torsion bars are between .88 to .94" It has been said that the Mopar spring rates were too soft up front and too stiff out back. I agree. I run 1.15 torsion bars on that red car above. The leaf springs are Mopar Performance 440/Hemi spec. Shocks are Bilstein RCD from Firm Feel. For sway bars, I have a 1.25 up front and a .75 (3/4") in the back.
Tires are a subject that always has critics. The really good handling tires are in a larger rim diameter than these cars ever had. The sticky tire selection in 15" rim size is very limited. 16" isn't good either. Mine are 18", a size that I picked because it allowed some sidewall for a reasonable ride.
If you are just looking for improved stock, as I stated, a good quality standard front end rebuild is a great start along with good shocks and tires. The torsion bars and sway bars can be added later.