Don't know a lot about your Protools rack. But,

You can certainly sync the H8000FW to Wordclock. See the notes in the manual concerning termination.

On looking at the 003 manual, it appears that it can be either a WordClock slave or master. Setting the Preferences to WordClock will make it a slave, so you should NOT do this if you are syncing the H8000 to WordClock..

The manual is correct about only one sample rate – this applies to all digital systems (except for sample rate conversion, but that is another subject). You will probably do best to make the ProTools the master and sync the H8000FW to it via WordClock as you propose.