That cage sounds very similar to the one my mate put in his rally 120Y. His is made out of cold drawn seamles steel. He has the diagonal and the straight bar for the fixing point for the harnesses both on the main hoop. His is all camms approved. Be carefull with the welds though, my mate had to get the whole thing checked out before it was approved, some of the welds wern't good enough (i.e. The weld wasn't hot enough to penetrate the metal properly to make a strong bond) so some had to be re done. It had the side bars as well, makes it hard to get in and out. It cost him about $1300-$1400 all up i think.
Anthony