This issue is a variant of The Best of DC (DC, 1979 series) #34 [Direct-Sales]. There exist further variants.
Issue number [direct edition only] on cover is "497." Likely a production mix-up with Adventure Comics [digest] #497, published in the same month.
Inside front cover.
"The Flaming Doom" and "The Nightmare Menace" printed as one long story.
combined with "The Day the Metal Men Melted" into one long story.
inside back cover