My guess (rightly or wrongly) is that the frame was built in 1978 but is a 1979 model. Current manufacturers seem to have next years model available from late the previous summer (if you see what I mean) and this could be the same, plus their is a chance that Peugeot may have made a batch of frames ready for assembly.
I'm aiming to get the frame sprayed in the same colour assuming I can get a decent colour match, otherwise it will be white. (I'm not sure on the ethical stance of getting a frame sprayed a different colour - ideally I would not be getting it sprayed as I feel that it will have lost some of its originality, but it's got one or two too many chips and scrapes for my liking).
I'm getting it done at Vernon Barker Cycles
near Sheffield. I've been using Vernon's services since the early nineties and remember going in his workshop back in the day and seeing frames for the likes of Malcom Elliot, Tim Gould and David Baker awaiting collection.
Like you I'm going for French bits - not as collectable as Italian bits, but a hell of a lot cheaper !
Too many hills - too little timehttp://velotastic.co.uk