CSR may well add a further $50 - $70 million to the asbestos...

CSR may well add a further $50 - $70 million to the asbestos claims fund. Something similar took place after the floating off of Rinker Group.
Upgrading the building side and Aluminium parts of the company, to maintain profitability, will surely cost at least $400 million.
The debt side will have to be very much reduced as well.

It looks more likely that CSR will plump for returning a bit less that half of the A$1.6 billion after tax to shareholders, to be on the safe side. (CSR returned 20c a share some time back and shortly afterwards had to raise cash by bringing back the share purchase plan.)