As far as I understand it, you only need an IFR "equipped" helicopter to demonstrate your IFR proficiency. The check ride can be performed during VFR conditions obviating the need for an IFR "certified" aircraft.
Also you don't need a type rating if there is a type certified pilot at the controls, either a safety pilot or the examiner. The check ride is about your IFR proficiency not your knowledge about that particular type.
I know, I know, you normally do your type proficiency and your IFR proficiency at the same time however you can do them seperately as well.