Andrew, with the benefit of hindsight I'll offer this advice. Always, always always start with the best example you can find. Right now this car has just come onto the market.
http://www.ebay.com.au/itm/Datsun-260z-2-2-auto-suit-240z-280z-300z-fairlady-drifter-/262268489352
It looks like an 'honest' survivor with a little bit of rust bubble here and there, but it's like not got serious (more than skin deep) cancer. A car like this would require a higher initial outlay but will pay dividends in the long run, as you'll spend more time enjoying it.
2+2s have started to pick up in value lately, I don't know if you saw the 280z 2+2 that sold for $70K AUD recently.
http://japanesenostalgiccar.com/2016/01/28/datsun-280z-2-plus-2-sold-for-45000-at-auction/
The reason it sold that high is because of originality and low miles, if you are looking at a car worth restoring the Blue 1 on eBay would be a better prospect, now and in the future but it all depends on what you want from the car.
I had a white 2+2 years ago and it was a disaster if I'm honest, lots of botched repairs, previous accident damage to rear 1/4 panel, everything was changed from it's original form and it gave me nonstop hassle. When it was written off I was kind of relieved. I've not regretted any of the other S30z's I've bought, only regret the 1 I sold, which was also my first car.