agree with Robbie uk on that.
great that the walls are in such a perfect condition - you can then use lining paper grade 800. Obviously, the condition of the walls can change without further notice ;) so it's good to have it lined as it will stop any potential/future cracks showing up...
try wallrock fibreliner. however, it's very difficult to compare with traditional lining paper as they are very different products. I'd say in terms of the thickness, wallrock in between 1400 and 1700 in lining paper terms. shout if you need more info.
Robert