Rather than the original overture, this recording contains an arrangement of sections from the "Polovtsian Dances." Presumably, that was used as the overture in the production.
The booklet for the CD issue of this lists the date of the recording session as having been June 22, 1965, but this would seem to be incorrect. That was the date the production opened. According to the issue of Variety dated June 23, 1965, the recording was made on June 20, the day before the first (aod only) preview.