I notice the ohm rating for the VP150 is 6 ohm. And read where they may be actually around 5.6 ohms. I can set my receiver for 4 ohms and up, or 6 and up.
Which should I set my receiver?

The "6 ohm and up" setting would be best for the VP150. The amplifier will see the load as 6 ohm given the entire impedance curve.