Ms. Gude is responsible for restoring both murals, using money she says the Chicago Public Art Group got from the NEA. (For a list of all the CPAG mural restoration projects in Chicago, see this link.) I'm pretty sure that the University of Chicago has contributed money for the 56th Street murals, as well.
She told me that she had restored Mr. Walker's mural once before, in 1993, and when she had contacted him to discuss it Mr. Walker said, "Why don't you just paint something else over it?" which was unthinkable to her. Mr. Walker's art is considered to be historically significant.
I know one of the models, the small-ish redhead in the tan coat. Her name is Rachel, and she was one of my husband's PhD students. She was not terribly fond of Hyde Park. She now works for the International Monetary Fund.