I believe the caption of the photos in Wings of Fame to be correct. Notice it says "later in its career . . . " which would indicate sometime after its first flight (26 December 1956) and it is also a test ship. "Arctic red" technically is insignia red, although photos suggest a brighter red was also used in later years. The advent of the fluorescent yellow-orange (and red-orange) in the late '50s was eagerly accepted by the USAF and US Navy, but only used for a few years as it erroded quickly as stated above. The use of "red" on test aircraft was for increased visibility, and test aircraft and other aircraft used "conspicuity markings" which is what we see here. The fluorescent paints were first used as conspicuity markings, and generally not as "arctic" markings. There are photos and drawings in Dana Bell's excellent article on arctic and conspicuity markings in the March 1996 issue of FSM, even some that show both "arctic red" and conspicuity Dayglo markings on the same aircraft at the same time (C-130s)!
I also see in the above photo that the red on the bottom of the wings is rather bright, leading me to believe that this is Dayglo fluorescent red-orange (FS 28913). Insignia red (FS 11136) would not look that bright in shadow.