The date is uncertain since it is not on the program.  Also I cannot remember the venue, but I believe it was on the Princeton University campus…
Mozart Mini-Marathon Concert at Spoleto Festival - 1973 The Columbus Boychoir participated in this multi performer concert.
Concert Program March 17, 1973 Monmouth Regional High School, New Shrewsbury, New Jersey
Concert Program March 19, 1973 Williamsport, Pennsylvania
The Choir List was dated 10/8/1996.
These are sample programs. No dates or locations listed.