The win is just North's fifth in 15 matches all-time between the schools, a series dubbed the "Unity Cup."
North took the first three bouts - by decision, major decision, and fall - to open a 13-point lead. South responded by winning the next five matches, including two by pin.
But what was crucial for the Indians during that South run was staying off their backs, and limiting state-ranked guys such as Tommy Trampe (heavyweight) and Danny Martoccio (106) to wins by decision.
After South's reigning state champion, Billy Rappo, pinned Micah Hayes at 113 pounds (in 2 minutes, 55 seconds), the Indians trailed by 24-13, but were in prime position to take advantage of their strength in the middle weights.
North (11-5 overall, 6-0 league) took five of the final six bouts, including the final four by pin. Alden Ely's pin of Dylan Moyer at 145 clinched the victory, and the visiting bleachers erupted into cheers.
"We kind of knew it was going to run that way, so we had to keep it close," North coach Tom Vivacqua said.
North remains the only undefeated team in conference and, with one match remaining against middling William Tennent, looks in prime position to win its first league crown since '09.
"It was one of our goals, a league title," Vivacqua said. He added: "If you were to tell me the first week [of the season] that we'd be battling South for the [Unity Cup], I would have called you crazy."
Since Council Rock High School split into two schools in 2002, South (6-6, 4-2) has amassed a laundry list of accomplishments: five straight District 1 North titles, three Southeast Regional crowns, five district team tournament trophies, and the 2005 PIAA Class AAA state championship.
League titles don't quite fascinate South coach Brad Silimperi.
"The only thing that matters is districts, regionals, and states," he said.
North's John Dutrow, the No. 6 132-pounder in the state in the PA Power Rankings, improved to 26-4 this season with his 43-second pin of Quinn Moore amid the Indians' run.