Could you post up pics of the cylinder heads, I've had a couple of Cavaliers before with the 1.7 Isuzu but I never took one out.
ColonelK has a Cav 1.7 which I assume is Diesel as there was never a 1.7 Petrol. You can search for a car
here. Try using both Opel (mainland Europe and elsewhere) and Vauxhall (UK only).
Here is a top image of a 1.7 TD (Opel).