I'd go with the 7 inch. I have 4" backspace 7" on mine with 225/50 tires, never rubs in cornering or anytime else.
Since the Granada rotor allegedly pushes the mounting surface out a tad, should end up just about the same net wheel/tire placement in the well as the setup I'm running. Plenty of room in the rear, I have run 245/50 in the rear on the same wheels without issue.