Try the following sources:
Wings magazine, June 1983, Vol 13, No. 3
Airpower magazine, July 1983, Vol. 13, No. 4
Lockheed U-2 by Jay Miller (Aerograph 3) published in 1983 (lots of detail & overall photos and line drawings in black-and-white)
Lockheed U-2 Dragon Lady by Dennis Jenkins (Specialty Press)
50 Years of the U-2: The Complete Illustrated History of the “Dragon Lady” by Chris Pocock
CIA And The U-2 Program, 1954-1974 (Plastic Comb) by Gregory W. Pedlow (Author), Donald E. Welzenbach (Author), J. Kenneth McDOnald (Author)
The U-2 Spyplane, Toward the Unknown by Chris Pocock (Schiffer)
World Air Power Journal, Vol. 28 Spring 1997 (lots of color photos)
All of these show markings for the different operators. The USAF and the CIA were the two major users.
The U-2 flew in several color schemes, the most common being natural metal and overall very matt black. The problem with the black (and IIRC, that’s what CIA used) is that when photographed, it looks like a black blob with defined edges. You can’t make out much detail. Maybe the detail shots in Miller’s book will help.
As far as the camera ports go, I can’t recall which – if any – of these sources show them but Cutting Edge (www.meteorprod.com) makes an aftermarket detail set specifically for the camera bay.
HTH