From the start my idea was to keep this at a minimal hardware level, ideally only the barely needed components.
If the antenna was suitably constructed, it should not even be necessary to put an separate antialiasing filter on it, it would be bandwidth limited already.
The A/D converter should be able to sample once per micro second, or one million times per second and have at least 8 bits. I was somewhat surprised that this made it a controlled ITAR item, but fortunately this has not affected me in any way.
The computer interface was the "here be dragons" bit, and I am still not satisfied with this, but simply put, this is just the glue between the software and the hardware. Correctly done, the job is much easier for the software.
The timebase can be anything which is stable enough to support the necessary integration period for the LORAN-C signal. A moderately good OCXO, Rubidium or Cesium will do the job.
The D/A converter is used to steer the timebase so that software can lock it to the LORAN-C signal.
And the software, of course, will do the rest.