Picts and price might help. Through 84 all used pretty much the same wires with a "normal" looking 8 post dist. 85 up used a pair of 4 post dist that mount on the face of the cam gear and have 4 posts sticking up like fingers on a hand.
Link to ad.
http://forums.pelicanparts.com/porsche-928-used-parts-sale-wanted/710142-beru-plug-wires-new.html#post7025564