Are you asking if it would be a good buy? If you are, I say hold out for one with front and rear lockers and one that has had the head gasket replaced already. You could probably find one with better paint as well.
I'm sure someone knows better than I, but I've head of the HG going before 100k. This is a common thing to replace on the 80 Series. I suggest check out the 80 Series Tech Forum on here and checking out Slee's buyers guide.
I actually saw this today. Looks like they dont really take care of it. I wouldnt pay 4500 for it. Mine is locked and in better shape, picked it up for 3400 in Forth Worth. And there is no set time on when a HG goes out. I have a friend with 217k on his and it has not needed it yet.