Pacific erased a 10-point deficit, surging back to take the lead as Trevin Harris and Tony Gill each sank a 3-pointer to make it 62-61 with 2:15 left.
Portland's Ryan Nicholas and Bock each made a pair of free throws, and Riley Barker followed with a layup to put the Pilots ahead by one.
Bock was fouled on the next possession and made both free throws for a 66-65 lead with 3 seconds remaining. Aaron Short intercepted Portland's inbound pass, was fouled, and hit both from the line for the final margin. Portland's final shot was wide left.
Harris led the Tigers (15-14, 6-12 West Coast) with 19 points.
Bryce Pressley paced Portland (15-15, 7-11) with 19 points and Thomas van der Mars had 17.