Looked it up in the Media Guide: vs IUP in 1986, 108-49, +59; vs Ohio Wesleyan in 1971, 103-48, +55; vs Army in 1929, 69-16, +53
Also notable, the last two 100-pt games were Houston Baptist in 2007-08 (100-62, not full D-I opponent) and Notre Dame in 2005-06 (100-98, scored in 2OT). The last regulation 100 seems to be Norfolk State in 1999.
I was shocked that I've never seen a 100 point Pitt game (since the start of 2008). Woulda thought that Sam/Dejuan/Levance team hit that at least once.