I say boost the Z..
Save on the side for a GTR and then who knows, maybe you will put that off a bit once you realize how much fun a boosted Z is
Also, downtime is not bad at all. Your talking anywhere from a week to a month if there are minor setbacks. Also, just run conservatively, have fun and avoid additional headaches.
Will surely keep you smiling for the next 2 years when behind the wheel.