Okay here is a list of differences. This is one of my better finds I think, I am curious to see how much this baby goes for on the bay. I predict it will fetch in the neighbourhood of $100. I also predict I will regret selling it some day but may be glad for the money when I am in Europe. There are, as I count, 3 distinctly identifiable versions of the record front derailleur from ~1960-1967. Hi-campy has the earliest one which fastens both arms with slotted bolts.

1) The text on the clamp is skinnier on the earlier one

2) The shape of the alloy body is different, there is an extra elbow on the earlier one
compare to above left
3) The part of the body that the limit screws are threaded into is refined on the later one, on the earlier one the shelf had to be machined or drilled to allow clearance for the arm.

4) The earlier one does not have a slot in the cable stop

5) The shape of the body which leads to the cable stop is different

6) The earlier one has nothing to secure either arm while the later one has the design we all know of the spring doing double duty to hold the lower arm on.
compare to left image in difference numbers 3 & 4