Have had a look through my old pictures and I am sure
its a three arm Stronglight cottered steel chainset on
Simplex rings, the type with the three arm bolt on
adaptors which give a six point fixing at the rings.
The Official Tour de France Centennial book has some
wonderful shots of Charly Gaul on this very set up
pp.183, pp.187.
Or you might be able to find it on this link which is
very interesting.
http://procycling.lequipe.fr/
Merry Christmas and lots of luck and laughter to you all in the New Year.
Thats all for now. Keep those wheels spinning, in your memories if not still on the road. Be lucky Mick Butler Huntingdon UK.