Thanks for the link TRI, but I'm afraid that I already came across these files a bit earlier in my search. Nonetheless, I listened to them the other day if for no other reason than old-times-sake. It was great to hear Crazy Roger's over-the-top New England-accented radio announcers voice again after all these years (sadly, I read somewhere that Roger passed away several years ago).
Some additional research done this week uncovered a scan on page 24 of the January 1981 issue of FRENDX. An entry in the loggings column would seem to indicate that this particular broadcast took place on the 15th of December 1980. This would make sense since the show in question included a kind of tacit musical tribute to John Lennon (the 15th being just a week after his death).
I dunno if this will get me any closer to my goal, but it WAS interesting to pin it down to a specific date (assuming, of course, that there weren't other Klaatu-related I interviews on other Radio Confusion broadcasts. My intuition tells me that there probably weren't).
Anyhow, the search continues…