Show different content based on radius of IP location?

Show different content based on radius of IP location?

I need to show a different phone number on the homepage based on the
user's ip location. It will be for a dynamic and changing number of store
locations. So if a user visits the site and their ip location is within 50
miles of one of our stores, that store number will be displayed. If we do
not have a store within 50 miles of their location, the default number
will be displayed. When we open a new store, we will add the phone number
and city (or zip, whatever is needed) into a custom field within
Wordpress. This data is what I need to use to do the geotargeting.
I have read countless articles and know I need to connect to a database
like max mind, but I can't figure out how to do the radius part. Can
anyone point me in the right direction? A plugin or free service that can
get me most of the way there?
Thank you.