N787RR is actually a 747-200B, and it has been flying around recently. I can confirm because I saw it over San Diego last week going out over the Pacific for a test flight.
Note: FA might not show all of its latest data probably from a glitch.
According to airlinerlist.com/ also indicates it is stored and has these comments:
Seen at Waco; will be fitted out by L-3 Communications Integrated Systems as testbed for the RR Trent 1000 (B787) engines 06.05, tests start mid-07