I suspect the reason that Chrysler used the front suspension items' relationship, rather than using body sheet metal (as many seem to like better) could well have to do with the build tolerances of the body itself . . . or ANY sheet metal back then, for that matter. As strong as those bodies tended to be, it was how they were welded togehter which determined a LOT of how the bodies ended up (sealing, windnoise, etc.) rather than just cosmetics, by observation. Certainly, there were production specs, but even those have their built-in tolerances. Which makes the front suspension items as what might be termed the most reliable way to do things.
One thing I noticed when trying to get the front end of my '67 Newport adjusted after the lower control arm pivot bushings were replaced, was that as the correct level was approached, the flat portion of the lower control arm (between the pivot and the ball joint), became more parallel to the floor surface. Too low, it sloped toward the oil pan. Too high, it sloped to the tire. When done, it should slope toward the tire a little or be completely parallel to the flat floor, by observation.
Once done, there is another measurement which might be easier to do AND see. The distance between the top of the lower control arm bumper and what it contacts. Sure, it might become a bit shorter over normal use, but it should still be reasonably the same height as when new. Easy to measure with the number of fingers that will fit in there, too, by observation. YOUR fingers rather than a "standardized finger width".
One reason the load-leveller type of shock does not tend to work on Chrysler products is that by the time the rear springs are used enough to need them, the center section (where the coils are closer together) is not strong enough to raise anything back to where it should be, so that puts the outer (wider spaced) coils into play. Which also keeps the rear end level lower than desired. End result, very little additional rise, which makes air shocks a better deal for those situations, as a more temporary fix. BUT a fix that can be better tolerated, from my own experiences on the '70 DH43N and '80 Newport I have (which had seen some lighter travel trailer use by the original owners). On the DH43N, I used Gabriel Hi-Jackers with great success. Has a 1.375 HD shock in them, so they ride firmer than the 1" piston in the Monroe Load-Levellers do. I liked them, personally.
Before the non-air shock operatives get too irate over my choice, consider why I did that, back in 1975. At that time, any spring work was usually limited to trucks with special needs for their job function, rather than cars. Getting new springs from Chrysler was not an option either, but would have been too expensive if it had been. Not really trusting the spring shops to "get it right", I opted for the Gabriels (which had the air bag protected by the shock housing extension). Certainly, the only other option would have been the AirLift air bags for the rear axle, which would have needed more engineering to make them work (although some successful drag racers had used them to pre-load their chassis for better quarter mile performance (more air in the rh bag than the lh bag on non-SureGrip cars, for example). So the air shocks made sense to me and made the car handle almost like it had a rear sway bar on it, by observation. Just 60psi was all it needed to level the rocker panels, with the minimum being 30psi to keep the bag from wrinkeling. Basically, no detrimental affects to the TorsionQuiet Ride in how I was using them.
Just my experiences,
CBODY67