I can't help you in the lift department but I will comment on the GV's offroad abilities.ÂÂ
Have your friend crawl under his ride and pay close attention to the placement of the cat converter and muffler. Then look at the exhaust pipe and notice how it is mounted below the rear end. The exhaust system is a very weak link for an offroad vehicle. Unless one is going to do dirt and gravel roads (and that's not four wheelin), the GV is worthless even as a semi serious off road vehicle. The first time you bottom out, the exhaust system will take a major hit. A couple of inches of lift and larger tires really won't raise the frame all that much.
Sorry to burst any bubbles about the GV's off road abilities, but that's how I see it... take it for what it's worth.