This is an interesting (although not terribly well-written) article about ongoing conservation efforts at the Air Force Academy, which is arguably one of the highpoints of mid-century Modernism in the United States.*
Although the renovation of the chapel is following the Secretary of Interior’s Standards for Treatment of Historic Properties, the overall approach to the project seems to be more Viollet-le-Duc than not, allowing the conservation architects to alter details to what they should have been, versus some of the compromised (and failing) details that were installed.
Link to the article.
* I have not had an opportunity to visit the Air Force Academy in person, but I hope to do so in the next few years, perhaps in conjunction with the completion of the renovation project