I don’t know exactly what you are trying to accomplish but you seem to be dealing with meta boxes. If so there are a number of meta box specific hooks.
do_action('add_meta_boxes', $post_type, $post); do_action('add_meta_boxes_' . $post_type, $post); do_action('do_meta_boxes', $post_type, 'normal', $post); do_action('do_meta_boxes', $post_type, 'advanced', $post); do_action('do_meta_boxes', $post_type, 'side', $post);
http://core.trac.wordpress.org/browser/tags/3.5.1/wp-admin/edit-form-advanced.php#L165
As well as the admin_head*
hooks
do_action("admin_head-$hook_suffix"); do_action('admin_head');
http://core.trac.wordpress.org/browser/tags/3.5.1/wp-admin/admin-header.php#L68
All of which run after global $current_screen
is set here: http://core.trac.wordpress.org/browser/tags/3.5.1/wp-admin/admin-header.php#L18