Re:
You might want to consider the Athena unit, by all accounts it's identical in every way and it's reasonable to assume that this was one of the units Campagnolo used across groupsets. Maybe someone else can shed light on any differences.
According to the 1992 catalogue the Chorus group used the Contax HS-01CO unit nd the Athena group used the HS-01AT, same spec, looks identical.