It's <a href="http://www.cams.com.au," target="_blank">www.cams.com.au,</a> but you need the CAMS manual, which costs approx. $40. It has all the roll bar specs. I'm not sure about Qld., but in NSW you'd have to speak with a CAMS registered Automotive Engineer, not just a blue slip garage. CAMS can supply a list of them.
If you are seriously considering competing in CAMS events, a CAMS manual is a must to avoid spending money on mods that are not allowed. I expect you are looking at Improved Production. The manual has a large section showing rollcage design and specs.