I'm wanting to ditch my OLD low hanging headers, are these manifolds worth it?

You could source a Magnum manifold off an early Jeep Grand Cherokee for the right side locally. If it has the big 2 1/8" outlet, they say it flows as well as a right HP manifold. And that is the hard to find (i.e. expensive) one too.

Left side you need any HP manifold for an A-Body. The Magnum one's have been made to fit but I don't believe it is a good fit.

That said, if you can grab the linked above manifolds then I would do so. That really is a good deal.