Captain Thunder is obviously based on Fawcett's Captain Marvel, who had had his own DC comic for a year when this issue was published (Shazam!). DC didn't introduce Captain Marvel into the main DC universe until December 1976, in issue 137 of Justice League of America.
Credits for pencils and inks confirmed from Julius Schwartz's editorial records, provided by DC Comics. [August 2007]
Includes reference to crediting the artwork in "Mr. Mxyzplk Returns" in Superman #272 to John Sikela based on info from Jerry Bails.