Rear sway bar for 1964 plymouth valiant

i get you.

keep in mind the basics: a big front bar induces push/understeer, and a big rear bar induces loose/oversteer, then match your "springs" accordingly with an eye toward balance of front and rear rates.

i'm also a proponent of softer spring rates and bigger bars, in that you can achieve some semblance of ride quality and still have decent handling. but that's a whole theory of handling that can devolve into squawking akin to an oil thread on a motorcycle forum.

anyway, a big rear bar isn't necessarily bad but when you have a high spring rate and the inherent design of mopar leafs short, stiff front section combining the two is a recipe for a very tail happy car.
I haven't decided on torsion bars YET, so I still have that open. I'm thinking maybe the stock 340 bars. It's a slant 6 car, so that "will" be an upgrade.