I should have remembered. The chromium intensifier uses hydrochloric acid, not sulfuric. If you bleach to completion and redevelop in a slow acting developer, you can stop when you think you are where you want to be. If you stop too soon you may be worse off than before. If you develop to completion, you will also be worse off than before unless you use a low contrast developer with lots of sulfite. I don't think you will do the grain any good in either case.