The UCA bushings get torqued on the bench before you install in the car. You do have to make sure the shafts are centered. What brand ball joint? I use only Moog parts on my cars.
If you have original type UCA it isn't necessary to have weight on them... I had mine setting on ramps when I tightened lowers...
My mistake it is the lower arm that has to be tightened with it sitting on the ground. As bmcdaniel stated above the upper must be centered and lubed good. Should put some angled grease fittings on it while you are under there even though you have the holes in the towers for greasing.
Gotcha! I rebuilt the UCA and they are centered and I had angled zerts but when I put the UCA in I had no room to get grease gun on fitting. Went back to straight ones through the towers. I am going to loosen the LCA eccentric and lower the car and see if that moves the suspension. As it sits right now I can't bolt the inboard lower shock mount on due to angle of UCA.
After re reading your first post ,I think your problem is at the lower ball joint.If you have tightened it enough to crush the rubber it is wrong. I think you might have Lincoln Versailles spindles .If that is the case Mustang Steve makes tapered sleeves to take up the difference.