Shop around. Most (if not all?) automatics will be a 'Fairlady Z', which are Japanese imports and a lot of independent garages seem to try to pass them off as a 350Z. These will generally be cheaper but you're better off looking for a UK GT manual spec. The automatics are 5 speed, manuals will be 6 speed.
The engine revision differs through three models, based on the year:
3.5L VQ35DE V6 (2003 & 2004)
3.5L VQ35DE RevUp V6 (2005 & 2006)
3.5L VQ35HR V6 (2007 to 2009)
I used to own the 2003 model, so I couldn't tell you how much better the later revisions are. Handling is pretty good and the drive can be a bit predictable but felt pretty stable throughout my ownership (1 year) I never tried drifting with it mind. It's 0-60, IIRC, is around 5.5-6 seconds.
My only real grievance was the limited rear view when parking, and quality of the plastic interior as it picked up a rattle in the center console which was a pain to find and stop.
But yeah, find a GT spec and give it a test drive. There's a thread devoted to 350Zs floating around somewhere here.
