I think you were right on the money with the year 1983 640, because it did come with campagnolo Gran sport pedals, campy hubs,Cinelli bar and stem. Here a picture of the head tube which I removed the white pin strips and I see red color paint under it.
Originally Posted by
beicster
It is not an 82 61x because they had the rear derailleur cable housing stop on the top of the chainstay. I am going with 83 640 which came with a Tange Levin headset, 531 CS frame and it came in black. The only thing off is that the 640 came with a red head tube. Is that usually a decal or paint?