No doubt this will not come as a surprise to anyone. We were correct is assuming that China has archival repositories other than the government repositories of the New China and it is quite likely that we walked right by the gem of them all!
The First Historical Archives is within the Forbidden City and a tour would have been possible. This repository holds the archives of the emperors and associated governmental affairs and activities, which date from at least the 13th century.
Some American scholars have regular access to the FHA and they would be able to facilitate the necessary contact for future U.S. archival delegations. One such contact is the Center of Chinese Studies at the University of International Business and Economics in Beijing, directed by Ron Anton of Loyola University of Chicago. The Center of Chinese Studies is engaged in research within the FHA, and besides facilitating contact, it would be able to present and comment on its findings.