Finer grained permission for managing node revisions by content type

Currently, users with 'administer nodes' can choose to create a new revision or not and this is a global setting. Enabling this for roles trumps many of our security controls for different node types, etc. We would like to be able to allow particular roles to have the ability to create (or not) new revisions based on the type of content. I'm sure there are a number of ways to accomplish the task; however, our hack to (node.pages.inc) was to introduce a new global permission for 'administer revisions'. This could be managed separately from the 'administer nodes' trump card.