IOH has the largest DSO deposit our of this list by far. Their JORC deposit was down to 200m, however recent drilling has low 60% Fe down to 300m.
As far as a takeover goes this will most likely be unsuccessful due to the majority share holders not willing to sell.
Are you interested in any of the South Oz junior Iron Ore companies? As soon as a new deep sea port is built a new Iron Ore region will quickly emerge.