Exactly what I was looking for. I can get the job done within 1 million characters (JSON string size in the script parameter). Sorry that I did not find that myself. No way I'm going to bring 3rd party plugins into the equation as I'm convinced a Filemaker script can loop through the content of a JSON string and update records accordingly.
If anyone has a good example of a script that parses JSON and loops through with record updates, fantastic. That's what I'll be building near term.
Data API call that initiates the server side script passing a stringified JSON object array containing the values to update into the existing Filemaker records.
Kirk