Well, here goes on the anorak reply! This is assuming we are talking European spec as American spec is different....
S2 prefacelift 1600 Spiders (and Coupes) should have the individual quad headlights set in silver plastic bezels with a silve "honeycombe" grille
S2 prefacelift 2000 Spiders (and Coupes) should have the twin lights each side set under the single lens and a black grille with silver bars at the bottom
All HPE S1 and S2 (prefaceflit) be they 1600, 1800 or 2000 should have the twin lights set under one lens - the grilles are the same as the corresponding Coupe / Spiders.
From S2 facelift all variants (Coupe, HPE and Spider) moved to the same front end treatment of the individual quad headlamps set in black plastic surrounds with the old 2000 style grille.
From S2 facelift 2, the Lancia family shield grille was fitted with the bigger bumpers (not spider as this never went to S2fl2 on European spec cars)
Simples!!
Hope that helps
Andy
Andy, these cars were assembled in South Africa from CKD kits too. My S2 coupe had chrome metal bezels around the quad geadlights with a black grille with silver bars at the bottom, the same as shown in a sales brochure I have.