Hi Mike,
I think its personal preference and use that puts you in the right Z ,i'd go out and drive a few i did, the 1.9 a great drive a smooth gearbox and still a great sounding motor. The 6 cyclinder cars are very smooth and the power delivery is almost effortless.
I looked at economy and the head said 1.9 and the heart said 2.8 personal i love the body style and stance of a prefacelift 2.8 and for me was what made it a must, i think i would have not been as happy in a 1.9 felt it was a compromise on what i really wanted.
Saying that looking at the stats for the 1.9 and 2.8 they appear very similar and on a run it gave me 31mpg which i thought fair for some lets say spirited driving on occasions
Good service history is a piece of mind, the engines after all are pretty solid engineering and looked after will go for ever. As said rust front wings bottom of rear wings and the sill covers, usually caused by stone chips but there are loads of examples out there, just be ready to pounce as the good one seem to fly away!!!.
Great car choice one you won't regret im sure happy hunting....