Bradley, who averaged 19 points, 10.4 rebounds and three blocks per game last season, when he earned first-team All-Mountain Pass League honors, said his transfer to CdM had nothing to do with basketball.
"It was really for personal reasons and it's complicated," said Bradley, adding that he moved away from his parents and into the area with his grandparents in June.
"This means everything. I'm really excited about [the decision]. I would lose sleep at night over this. I couldn't picture myself going to high school and not being able to play ball."
Bradley joins a CdM team, which is coming off a 24-4 season in which it won a Pacific Coast League title and reached the quarterfinals of the CIF Southern Section Division III-A playoffs.
With a big and athletic body in Bradley, the Sea Kings are section title contenders again.
Returning for CdM are senior guards Danny Cheek and Clayton Ragsdale, who shared the Newport-Mesa Dream Team Player of the Year award and earned second-team All-CIF Southern Section Division III-A laurels last season.
Schachter said he is happy for Bradley after his grandpa, Jim Hauke, who is Bradley's guardian, appealed the denial through the state.
"I was very disappointed in the original decision [by the CIF Southern Section]," Schachter said. "I felt bad for Marcus and his family, but now we can move forward."
The goal at CdM is to raise a sixth section boys' basketball title in the gym. The previous one came in Schachter's first season at the school in 2006-07.
"We have really high hopes," said Bradley, a Montana State and Army recruit, who is not the first in his family to attend CdM. "My mom, my aunt and three uncles went to school here and I like it here."