why is it impossible to find new small ball joint a-body complete control arms

You can ask Hotchkis to swap the a-arms for their small ball joint arms. The large ball joint is what they include in kits as a start as they assume people want the large ball joint to go with the disc brakes and 4.5 bolt pattern. I spoke to them 6 months ago about this and the tech rep said as long as they were not used and as delivered they would exchange them.