Parts supply house
As for local parts houses in Boise, I usually take my business to General Auto Parts at 28th & Idaho. They are an independently owned NAPA store, and the old guys behind the counter actually know something. I take most of my machine work there as well. I drive right past a Schucks and a corporate owned NAPA to get there.
If you kept the 67 K-Member, you will need a 67 idler arm, they were a one-year-only deal. Everything else can be for a 73.