Hello Jack and all,

you wrote:

>It comes back to using something like SL with its QRSS
capabilities. I wish I had a good file that worked at 8720kHz
for QRSS600 as an example. This would be a good start if nothing else.
<

It's not that difficult to set up. The key point in SL to get into the microhertz-resolution is the decimation (of the sampling rate), along with complex frequency to have a complex FFT spanning just a few Hz around the "frequency of interest". The effect is similar as a super-long FFT (concerning the frequency bin width, and thus the "gain"). I think on Stefan (DK7FC's) site you can find some configuration files for QRSSS.

Back in the "old days" of extremely slow Morse, I wrote this short how-to (for Spectrum Lab):
http://www.qsl.net/dl4yhf/speclab/qrss_quickstart.htm
  (it shows how to pick one of the VLF transmitters to stabilize the soundcard's sampling rate,
  a bit out of fashion since good GPSes with sync output became available, but anyway..)

To make the FFT window even longer / frequency bins even shorter than used in the default settings,
use the option 'complex input for the FFT with internal frequency shift', as shown at
http://www.qsl.net/dl4yhf/speclab/settings.htm#fft_size

And, last not least, there an explanation of FFT length, decimation, windowing functions, resulting resolution / effective receiver bandwidth versus dynamic range, etc:
http://www.qsl.net/dl4yhf/speclab/fftinfo.htm

All the best,
 Wolf DL4YHF