No expert but from what I hear the 16v is a better engine.
The mileage on that first one is unlikely to be genuine, if you read the text a bit closer they've only got a 5 digit speedo so it will have been round the clock once, twice,who knows! Ha ha yep check this out:
http://www.carjam.co.nz/car/?plate=zd6307Not bad prices.
I bought one recently that had already been modified enough to make it a decent little offroader - if you look at it on paper it was cheaper to do it that way than buy the bits myself. Of course then you're running the risk of not knowing how well it's been done etc, although in my case it was a truck from the club I'm in so that wasn't a concern.
Are you a member of any clubs? That might be a way to go.
Don't rush it, did that with the last truck I got and regretted it straight away.
If you've got any specific questions fire away, or you can have a look at mine depending on where you are.