Hello, I am mounting a Nightforce 5.5-22x56 NXS scope to a Remington Sendero rifle in a Magnum length action. The Barrel is being replaced with one of similar profile, maybe a bit thicker and 30" long. With the one piece Nightforce mounts to suit this rifle and scope combo, what height rings should I purchase to suit the 56mm lens? Also can anyone recomend where I can purchase them from and have them shipped out to Australia................ Thank you.