You can try the rust convertor, but in my experience it will only come back and still grows underneath the cover-up.
I would recommend that you use Oxi-Solve or Pickle-X (sp?). This actually removes the rust (may take a few applications) and leaves a phosphate coating which promotes adhesion. You apply the stuff on the bare metal and then, let it set for about 20-30 minutes. Next, you rinse with water (yes water) and the water reacts with the chemicals to create a phosphate coating. The same type coating that OEMs use to protect bare metal prior to paint.
Eastwood caries the Oxi-Solve product and you should (no, make that must) wear gloves during application. The stuff will eat you up if you don't. Here is a picture of my hood that we applied the Oxi-Solve to. It left a great finish on that was ready for primer.
As Stefan noted, it is also a good idea to fully remove the rust by blasting.
Hope this helps...