Sorry to be the bearer of bad news, but this may not be not a model 630 with the Reynolds 531 frame. There is a good possibility of it being the lower model 620 "River Doubs, by virtue of the cable stops brazed onto the top tube. Jeunet's Reynolds 531 frames typically used cable clips versus stops. You can determine the actual model by measuring the size of the seat post. A Reynolds 531 frame would use a 26.4 - 26.6mm post. I'm not sure on the correct post size for a 620 frame, but I suspect it is something under 26.0mm.

Edit: The steel post and lack of shifter braze-ons also point towards a model 620.