Gil, Larry I am running three of my Stuart boilers sans any insulation after ditching the asbestos. Everything that I have bought and tried in the past had its downfalls, the major being that they still released fibres.
This material when I felt it through the packaging was very stiff but could be easily shaped and the ceramic paper is sandwiched between two sheets of aluminium.
I think its made by these people
http://www.gasketsolutions.com.au/html/heat_shield_material.html its states 'flame proof' so I will write to them and ask them some questions about the product.
There were two sheets in the package and each sheet was pretty large. There'd be enough material to do a fair few fireboxes.