Jonno - I am yet to get the focus over to you for its detail, but maybe it would be worth showing you the genuine 2 owner datsun 1200 ute I picked up for $3K?
Sure, its not a ground pounder, but with a few bucks dropped into the front end for ball joints etc, and a good service, it is without a doubt, the most fun car I have ever driven, and when it cops the dogleg 5 speed and 32/36 weber in the next few weeks, it will be even more fun
My point is, dont be afraid to go for an early car. Datsuns in particular have a massive cult following, and I can buy pretty much any part I want off the shelf. Even hand made replacement panels for rust repairs etc are all available on ebay, and the car specific forums have SO much info on them, I reckon its the best way to get your hands dirty and learn some stuff about cars there is.