Please choose:
Wait for the permanent ward manager. It is not the right moment to go over anyone's head.
Share the data informally with the interim manager. See if she is willing to take it forward.
Speak first to the two colleagues who said they would support me. Agree a collective approach before doing anything formal.
Present the file to the board — with your two colleagues, with your names on it, formally — now, before the right moment becomes the never moment.