What you are talking about is tombac which is totally different then Salloum. I am smoking some Iranian tombac now as a matter of fact.
I've got an article up about smoking unflavoured black stuff here: http://www.hookah-life.com/events_6.htm
I would suggest changing the hole pattern to columns of 3 small holes spaced about 3/8" U.S. apart. Beyond that everything is on target.