I'd try a cheap set of clamp on slapper bars. The idea that you can't use them on Mopars is just plain stupid. It's a piece of metal with a rubber bumper on it, it doesn't care what you put it on. Are their better choices? Sure. But in the end all you are doing is stiffening the front section of spring.

Any car guy alive in the 70s knows slapper bars were a Day 2 item on most every leaf spring street car no matter what brand it was.