BTW - I think that a one-way car rental from Kanazawa to Takayama (or vice versa) is worth considering too, since it frees you from the bus schedule and opens up the possibility to explore the mountains. Depends how averse you are to driving.

EDIT - Alternatively, a one-way rental that ends at Komatsu airport. Not sure how that would fit in the overall itinerary, but it just occurred to me.