Gedday there Bandicoot .. A good choice vehicle and everything that Bulldog has posted above is spot on with regards Landcrusers whether they be a Troopy or a Trayback.
Personally, I'd be very carefull with the pop-ups .. Most of these will be ex hire campers and that usually means flogged to buggery and probably poorly serviced.
Like any thing mate, take your time and research the market. It's all about your budget and consider as well that you will probably want to have an extra two or three grand up your sleeve to bring the vehicle up to your required personal specs.
A well presented, lovingly maintained diesel powered 75 Series with as few previous owners as possible is the go .. Without being silly about about it, odometer reading, older 2H or later in the series 1HZ power plants aren't as important as the maintenance and care history.
And whatever you do .... Check for rust! .. and especially in the chassis members. Never, ever buy one of these things from someone who spends every other weekend surf fishing! .. (Or beach detecting).
Get the right one, from the right owner and at the right price and you'll have a vehicle that with still have many years left in it to take wherever you want go.
Good luck to you mate.