You would use the BETWEEN
variation of the meta_query, and you would need to use a meta_query instead of the simple meta_key, meta_value parameters in your pre_get_posts filter (i’m assuming that’s what you meant the you said bottom of the page you linked to)
$meta_query = array(
array(
'key' => 'height',
'value' => array($min_height, $max_height),
'compare' => 'BETWEEN',
'type' => 'NUMERIC'
)
);
$query->set('meta_query', $meta_query);