Don Newton also did a Shazam (Captain Marvel) two-parter in Adventure Comics (Digest) #491 & 492.

Being digests they can be somewhat harder to track down than regular-sized DC comics. It certainly took me awhile before I eventually got them, but they have never been reprinted since.

http://www.comics.org/issue/358596/

http://www.comics.org/issue/358597/?style=default