The Flames (16-11, 7-7 Big South) closed the game on an 8-0 run in the final minute -- all at the foul line -- and led the entire second half, by as many as 14 early in the period. But the Bulldogs (12-15, 7-7) rallied to within one on David Efianayi's layup that made it 59-58 with 6:29 left.
Kemrite's catch-and-shoot 3-pointer coming off a screen with 1:54 left gave the Flames a 69-63 lead.
Scottie James had 14 points and nine rebounds, and Pacheco-Ortiz scored 13 for Liberty.
Efianayi scored 19, Liam O'Reilly added 17 and Cornwall 15 for Gardner-Webb.
Mannion, who recently reclassified and is ESPN's No.11 overall player in the class of 2019, chose Arizona over Marquette.
He'll fit in with Sean Miller's plans for a faster tempo on offense.
The cream of the crop of American high school basketball will congregate in Colorado Springs from Oct. 5-7, as USA Basketball unveils its newly expanded Junior National Team minicamp in collaboration with the NBA, NCAA and NBPA.