Rivers was later, much later, in the 2010s. He was working with John Murphy. That deal was to have one "repertoire" concert one semester and then a "new music" concert the next. Sam performed one night and then gave a clinic the next. I drove up for both because, hey, Sam Rivers.
The others might have been before you arrived. Some were there for the Spring Lab Band Extravapalooza, others just for one-off "workshops". I very much recall that Clare Fischer brought along his chart for Lennie's Pennies, but I forget who played bass sax on it. But Gary Foster was there to add some flavor, which he did. No Warne, though...
Oh yeah, one more I remember was Ran Blake, who did a quick hit-and-run. He was just starting his Third Stream Deparment at NEC(?) and was barnstorming music schools looking for recruits. AFAIR, not luck at NT!