Matthew Dellavedova added 11 points and six assists for the Gaels (15-4, 4-1 West Coast), who never trailed.
St. Mary's held Portland to 43 points in the schools' previous meeting, on Feb. 23, 2012.
Paul McCoy made his long-delayed debut with Saint Mary's, with one rebound in three minutes.
The senior guard and Portland native transferred from SMU after the 2009-10 season, sat out the following year per NCAA rules, then missed all of last season after suffering a second knee ACL tear. He averaged 13.4 points as an SMU freshman in 2009-09.
Former Kentucky guard Ed Davender, the only Wildcat with at least 1,500 points and 400 assists, has died. He was 49.
Guard Naz Mitrou-Long, whose 2015-16 season ended in December due to hip problems, has been granted a hardship waiver for the coming season, Iowa State said.
As the Sooners look to life without superstar Buddy Hield and his sidekicks, it's clear their unseasoned players will need to grow up fast.