Is it really already thirty years since the mid-70s? Well, those days don't seem exactly like yesterday, but they certainly don't seem that long ago.
I reckon that the choice of components on a top level racing bike would have depended what type of racing you intended to do, ie massed-start road racing, or time-trialling. The out-and-out massed-starters seemd to be a litle more conservative in their outlook, ans the full Campag. group was the choice of most of those who could afford it. Otherwise it was a mix-and-match approach using mainly French components such as Stronglight for the chainset, Maillard 700 for the hubs, either Simplex or Huret gears and Universal or Mafac brakes. There was some Zeus equipment used but not as much as Ron Kitching, the importer would have liked, primarily because he pitched the prices almost as high as top-end Campag..and naturally folks went for the Campag.
For testers, they tended to be more choosy and innovative, the main and often deciding factor being the weight of a component - the lightest of its type often being the natural choice. Brakes were often Weinmann 500 as these were claimed to be the lightest and, of course, they were relatively close-clearance, but I specced quite a lot of CLB - genrally light, compact and just that bit more esoteric. Gears were often Huret, especially the Jubilee, occasionally Simplex, but very often Campag, and sometimes Zeus. As for chainsets the traditional TA was very popular, Zeus more common than on massed-start bikes, and sometimes Campag, sometimes Stronglight. The choice of hubs as far as I can remember called upon choosing large-flange ones, with 28 holes, sometimes with radial spoking on the front wheel. Maillard 700s were popular, Campag as usual were relied upon by many, but I recall that the Pelissier 2000 sealed-bearing ones were very much in demand ( or perhaps that was a few years later). I think that rims tended to be either Mavic sprints - OROs - or Wolber.
The other memory in respect of the testing bikes - the 70s was the era of "drillium" components. Alf Engers, one of the UK's finest riders against the clock, used many drilled components, including Weinmann 500 stirrups. Probably the slighlty greater use of Zeus components was due to the drilled chain-rings...or were they slightly later too?
Slightly later I remember supplying quite a lot of road bikes with Galli and Gipiemme groupsets..and of course the "tout Mavic".
Norris Lockley...feeling distinctly long-in-the-tooth = Settle UK