Hello @Corey Dozier !

If you will use this BxSpacesSearchResult.php (UNA 14.0 - RC5) file instead of default one, then you will have the possibility to filter parent spaces only with the next code of your custom service block:

array (
 'module' => 'bx_spaces',
 'method' => 'browse',
 'params' => 
 array (
  0 => 
  array (
   'mode' => 'parent',
  ),
 ),
)