Hi David, welcome to the club! :)
IMO the 2.8 is a lovely engine, although these days it will seem fairly thirsty for the power it produces. The 1.8T Quattro models tend to be more popular and can offer similar levels of performance from a lighter more fuel efficient engine, but make sure you get the 180PS version. That being said, I can understand if you want to find the top of the range 2.8!
I don't know massive amounts about these engines but definitely look for a well cared example with lots of history.
Also, check the heating system and temperature gauge performs as it should as I believe these can be common faults with this model along with radiator leaks. Obviously, with the car getting old too, check all the buttons/electrics work as there will be plenty of functions if you get the top spec version.
Let us know how you get on B)