He didn't know about the pre-load adjustment? Bloody hell!
I personally doubt that a pre-load adjustment or lack thereof would cause the noise that you describe, but a bad HLC certainly could. Randy Starkie bought a 380SL that was believed to have a bad rod and the problem turned to be a couple of HLC's (he did several posts on this).
It's not beyond possibility that one of the new ball studs has a bad HLC, or that one of the oil passages that feed it is plugged and so it takes a while to get pressure up.
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe