Why would it need a skyline box? there is a few direct fit options that will easy handle that power, tried & tested Bara box etc. As with the diffs loads of people run 500 and above with uprated cossie stuff and they are reliable.

Out of interest how many cosies out there actually run a skyline box and diffs? I can only ever recall seeing a couple of cars that actually have the box fitted, don't think I ever seen the diffs fitted as well.