Well that's mighty weird. Because I even remember what else I had on that shelf too. Three Buck Rogers novels: Armageddon 2419 A.D. by Philip Francis Nowlan, the movie novelization by Addison E. Steele, and That Man on Beta, also by Steele. I also had 3 Flash Gordon books: the movie novelization by Arthur Byron Cover, and the first two books of the six book set by David Hagberg: Massacre in the 22nd Century and War of the Citadels.
Here's another thought: Anyone know of an alternate cover/spine for Last Son of Krypton that was in black instead of white? I have been known to collect multiple copies of the same paperback book when there are alternate covers. I had several versions of Blish's Star Trek 2.
And yes, I do remember that Cover's Flash book had a black....cover.