RE-DIRECTING TO REGISTER Based on Permissions

[MacroPhotoPro]

I have a custom vBB page, and here is where I am trying to insert the code:

<?php

// ####################### SET PHP ENVIRONMENT ###########################
error_reporting(E_ALL & ~E_NOTICE);

// #################### DEFINE IMPORTANT CONSTANTS #######################
define('THIS_SCRIPT', 'srcImages');
define('CSRF_PROTECTION', true);  
// change this depending on your filename

// ################### PRE-CACHE TEMPLATES AND DATA ######################
// get special phrase groups
$phrasegroups = array();

// get special data templates from the datastore
$specialtemplates = array();

// pre-cache templates used by all actions
$globaltemplates = array('IMAGE_HOSTING',
);

// pre-cache templates used by specific actions
$actiontemplates = array();

// ######################### REQUIRE BACK-END ############################
// if your page is outside of your normal vb forums directory, you should change directories by uncommenting the next line
// chdir ('/path/to/your/forums');
require_once('./global.php');
$navbits = construct_navbits(array('' => 'Image Hosting'));
$navbar = render_navbar_template($navbits);

// #######################################################################
// ######################## START MAIN SCRIPT ############################
// #######################################################################


if (is_member_of($vbulletin->userinfo, 1, 2, 3, 4))
{
 header("Location: " . $vbulletin->options['bburl'] . "/register.php");
}

--------------- Added [DATE]1428683561[/DATE] at [TIME]1428683561[/TIME] ---------------

I think it might be easier to just list the user groups that can access the page.

What would the code be for that?