This probably has been settled long ago, but in case it hasn't - I found this looking through old magazines...
Daniel Rebour's article from the 1962 Salon du Cycle in Paris has a drawing and mentions: "The completely new CAMPAGNOLO, type "RECORD", etc." (my translation, original in French)
(Le Cycle, October 1962, p. 10)
The drawing very much looks like the Campy Record (chromed) derailleurs I have seen, so it may be the definite production model.
Please note that I am NOT claiming that the derailleur was available in 1962 or thereabouts.
Jan Heine, Seattle
Editor/Publisher
Vintage Bicycle Quarterly
http://www.mindspring.com/