AJAX and JSON with perch

Do you mean within Perch, or do you mean on your website where the content is managed by Perch?

Yes, that's no problem. The simplest way is probably to use perch_content_custom() and the skip-template option.

echo json_encode(
    perch_content_custom('Region name', array(
         'skip-template' => true,
    ));
);