Please see if the workbook v10.2 attached in the Forum Thread is closer to the goal.
I think it was mostly there.
On the Data Source page, I joined the two sheets on a calculated field of 1.
This created all of the combinations, which was then filtered down using
a distance parameter:
[Distance (in Miles)]< [Distance Parameter]
On the Dashboard, I added a dashboard action to show just the near zips
when clicking on a store's dot, and I filtered a table to show the list of zips
within the Parameter range.
272199map.twbx 173.9 KB