Plugin using global_complete hook, cant exclude from a forum using if conditional

[basketmen]

This is replacement code from kh99, using global_complete hook, its works good

$find = 'Post New Thread'; 
$replace = 'Create a Listing';  

$output = str_replace($find, $replace, $output);

but now i want to exclude a forum
already tried wrap it using below if conditional, but its not works

if ($foruminfo['forumid'] != 123)
{
}

if ($thread['forumid'] != 123)
{
}

if ($post['forumid'] != 123)
{
}

what is the right if conditional? or this cant be done because its using global_complete hook?
please help guys