I have the same SA and I also have a GPSDO that I just finalized recently. I remembered that some time ago I adjusted the reference oscillator in the SA using just a Ublox GPS module set to output a 10MHz frequency and watching the drift on an oscilloscope. I was curious what's the result of that adjustment now that I have a reliable GPSDO.
Here's the result after about 4 - 5 hour warm-up. It was within 3 - 4 counts after about 2 hours.