Haha, don't get me wrong, i only own a Suzuki serrai, I don't think i've even ever touched a skyline. However, logically, you can pretty easily determine that if your engine goes, its either going to be because of some catastrophic failure (eg, oil pump), or from general wear. Ask the guy who built the engine how high it should be reved, get a good oil pump if your worried about that shitting itself, and set your rev limit accordingly. Remember, redline at 7000 or 8000rpm isn't going to be a huge difference in wear, especially if its not a full time track care and will be seeing a lot of time putting around the suburbs at 3000rpm anyway.