Eitan Chemerinski had 15 points for the Big Red (5-8), who had been 0-5 on the road this season.
St. Francis (Pa.) has lost 13 games in a row dating back to last season.
The Red Flash closed the gap to three points at 58-55 on Greg Brown's free throws with 8:33 to go in the game, but baskets by Peck and Galal Cancer made it 62-55 at 7:38.
The Big Red opened an 11-point advantage at 74-63 at the 2:50 mark on Gray's 3-pointer and cruised home to the victory.
Mike Brey is looking at former Notre Dame players to fill two assistant jobs that have opened up with the departures of Martin Ingelsby and Anthony Solomon.
Purdue's 2016-17 prospects got a jolt Wednesday when forward Caleb Swanigan announced he will return for his sophomore season.
Clemson's Jaron Blossomgame says he is withdrawing from the NBA draft and returning to school for a final season.