Welcome, John.
Maybe if you give us a hint where you will be installing this CBU the issue of correct pookey would become more clear. Or, knowing Royce, maybe not.
But wherever you decide to pewt the stuff, you either need to use the manufacturer's approved fasteners or take your chances on your own choice. If you contact the manufacturer and tell them what you have in mind, they might sanction it. Phone call's cheap.
My opinion; worth price charged.