Hello Lee,
Yes, the recordings were made Feb 11, 1958. This album is part of the "Felsted Series", which were stereo recordings offered under the MJR (Master Jazz Recordings). I have probably six different Felsted Series recordings (MJR) and they have incredible separation, so the individual musicians are featured all across the Soundstage. The presence is really outstanding. I built the 700b to the dual mono specs and the separation is very noteworthy.
One of my favorite albums for realism, the Septet and Quintet are right in front of you, front row seat! Felsted prided themselves on the realism.
Outstanding for any era, but really cool for 58'.