I just sent the vendor a message about the headset on Amazon. There is no info there about stack height, crown race, ISO dimension, or crown race. I guess the vendor has NOS parts because I don't believe these headsets have been made for a while.

The A9 was, IMHO, the best headset dollar for dollar ever made. Most other really great headsets cost a bomb. I grew up in a city--new orleans--that has terrible roads. Working in a shop, I saw a bunch of bikes with high quality headsets come back with issues as the bumpy roads would damage the headsets. We'd install an A9 and the problem was solved.