Zeus lugs and crowns were not exclusive to Zeus bikes, however, Colnago (and TREK) lugs and crowns were exclusive to those brands of bikes.
Raleigh used a lot of zeus frame parts in the late 60's and early 70's, and I have seen several Zeus crowns for sale, either on ebay or at least, in the possession of a photo-forum for a framebuilder or two.
So it's not surprising to find a fork made with a zeus crown and a campagnolo dropout, just about any custom builder could have made it.
- Don Gillies
San Diego, CA, USA