This bike hits many "perfect steel bike" points: 1) steel 2) nice steel 3)lugged 4) steel fork 5) super tight race geometry 6) vertical rear dropout 7) classic horizontal top tube, only missing out on being a 64cm, but hey! Now to look for more things!

As to something edifying for you, cool find! Looks good, and I dig the color. The 6400 pieces are nice (I'm in the middle of building up a groupset), though the crankset is, IIRC, a 620x of some kind. Something like a 6207 or 6208. These later 620x cranksets are to me, hands down the prettiest and most classic of the 1980's cranksets (7400 DA stuff being at least one of the others). They look simple, strong, and elegant, and they easily match with other parts. [600 Arabesque cranks, though visually different, are also beautiful] The engraved letters and numbers don't wear off, etc. I am curious as to the one-ended brake track wear. The difference would drive me nuts but hey, they came attached to the rest of the bike and the hubs matched. You can certainly address or not address that later depending on what you feel like. How does it ride?