School me: 63-66 Dart vs 67-72 Dart suspension

Well, are there fiberglass leaf springs made for it? If I can reduce some of the weight on the axle that alleviates my other reason for going with a 4 link. I can make a Watt's link so even if the rear does move I can fix that problem. I know I need to go to the later front spindles for brakes but I guess I can cross that bridge when I get to it. . As far as the front and torsion bars, what is that like? Any vendors there?

I didn't really like the early A bodies but as weird as they are I kinda dig em now.