[development] node access issue

Hi, I have just been given a hairy request from a client and need to guidance to what would be the best method of doing this. The site is a heavily customised drupal 4.6 which is running the organic groups. Organic groups is using the node access table already, which causes a conflict with the node_priv_by_role module. But what they want I think maybe able to be done via something else, but I am not sure what. Basically they want is for anonymous users to only access a few bits of content, and nothing else, where as authenticated users will see everything there, which hasn't been restricted by organic groups. Any ideas will be much appreciated. Gordon.