Configurations and Profile Options that Function across Operating Units

My client operates a diversified manufacturing company where each division operates as a semi-independent company on separate ERP instances.  They are interested in potentially consolidating a couple divisions onto a single Oracle R12 instance in separate operating units, however, they would like these divisions to maintain a fairly high degree of autonomy. For example, they would like to maintain separate ledgers and item masters.  I'm interested to know if there is existing documentation or a straight-forward way to identify configuration settings and profile options that are shared across operating units so that we can better understand the degree of autonomy that they will be able to maintain