Yeah man you got a problem alrightee
I'm guessing the UCA bushings are pretensioned, possibly the lower as well, but probably not.
New test;
Jack that assembly up to about the midpoint of travel, with the scale as before. Read the scale.
Then loosen the LCA pivot pin a couple of turns and smack it with a brass hammer to loosen the pin from the tube.
Read the scale.
Ima thinking it won't change much, but I gotta rule it out. Leave everything as it is.
Here's what I'm thinking; I have seen this before; The UCA adjusting bolts are probably seized in the bushings. The alignment guy, just reefed on them during the last alignment, and twisted the bushings up, putting a serious preload on the system. If I'm right, the next part of this test will prove it.
OK Part 2
Read the scale. If it is less than 100 pounds, crank it up until it is about there; but make sure you are not compressing any bumpstops.
read the scales again.
Slowly loosen the UCA adjusting bolts, watching for the cams to unwind. If they don't unwind of their own selves, they may be pinched in the saddles, so give the bolts a few bops with a brass hammer while watching the scales. If I'm right the bushings will unwind, relax, and the weight will fall to whatever that assembly weighs which should be less than 100pounds, Ima guessing 45/55 pounds.
If that happens, try to drive the bolts out. I bet you can't. I have had to torch those off and replace both bushings and all the hardware. But when I reassemble them, I coat the bolt shanks with anti-seize.Just the shanks.
There is a slim chance that your ball-joints are too tight. Moog or TRW joints are pretty good. But all others are built differently and tend to be extremely tight when out of the box. But tend to get extremely loose in the first hundred miles, or less.
You will know if the joints are too tight, while driving, because, the steering will not self center, and you will be steering the car back and forth ALL the time, because the dang car continues to go in whatever direction you steer it. This is extremely frustrating because the alignment can be perfect, yet it's a PITA to drive.If this has ever happened to you, in all likelyhood you didn't drive it 10 miles before turning around and returning to the installing shop.
But if you have NOT experienced that, then your BJs are not too tight.
By this point, if the problem has not surfaced; I'm out of ideas.
Now, if you end up having to replace the UCA hardware be advised that in the MOOG A-body kit parts, the threading on them is too short, and they will not properly clamp the bushings in the saddles. You will have to get some hardened thick washers on there to move the nut down the shank into the threaded area.
Also, do not tighten any of those pivot bolts until the alignment is done and only tighten them at or near the final ride height, so you don't have a repeat of pretensioned UCA bushings.
Also; do not tighten the lower shock bolt, until the car is at ride height.
Also; be advised that even after everything is working right; anytime the suspension is not at ride height,going up or going down, it will be twisting up the bushings, and you will read that on the scale as increased weight. This is normal. The trick is that at ride height, the scale should read whatever that assembly itself would weigh when off the car, or near to it. And weigh more as the bushings get twisted.
Ok I almost forgot; I see how the assembly sticks just before full rebound. IDK what might be doing that, but my guess is that, that is the relaxed point of the UCA pretensioned bushings. Ima guessing. My second guess would be that the Upper BJ could be sticking there. But, If you put the shock back on, I think you will find that the suspension never naturally gets down that far.