Bridwell and Schaffenberger bring back Black Adam, one of Captain Marvel's greatest foes, in Shazam! 28 (March/April 1977).
Sivana is in Boston in this issue, and still has the regeneration machine he created in the previous one. He uses it to bring back Black Adam, making his DC debut. Sivana expects Black Adam will do his bidding, but quickly finds out that is not the case.
Billy Batson is also in Boston, and gets caught up in a bussing protest. This sequence is really poorly done. It's all white people, and the whole thing makes a shallow mockery of the issues behind the protest.
The bussing thing also has nothing at all to do with the story. We get a brief recap of the origin of Black Adam. He was created by Shazam, the same way Captain Marvel would be, thousands of years earlier in Egypt. He used his powers for personal gain, so Shazam banished him.
The story also recaps his one previous outing, in Marvel Family 1, in which it was Uncle Dudley who tricked Black Adam into saying his magic word, stripping him of his powers.
There are a number of Boston locales used in the issue. Captain Marvel and Black Adam battle in and around Boston Harbour, where a re-enactment of the tea party is going on. As with their original battle, Captain Marvel and Black Adam are too evenly matched for Cap to triumph.
And, just as in the original battle, it's Uncle Dudley who saves the day, intentionally being stupid and pretending not to recognize Black Adam, which goads the villain into saying Shazam.
Black Adam returns the following year in the All New Collectors' Edition Superman vs Shazam.