I doubt it was filed with paint. See new picture I posted with Brev. Campagnola stamped into frame Only marking on bike frame. I thought of that. I went over it with a fine tooth comb looking for that possibility

Now that is a possibility. None of the Frejus frames I have seen have the detail this one has on the joints. The guy I bought it from did tell me it was hand made

I'm thinking this frame must be from about the mid 70s, with the long dropouts and the braze-on bottom bracket cable guides and shift levers, unless they were added at repaint. I'm not sure Frejus drilled the bottom bracket shell, though that could've been done later as well.

What, if any, is the date on the rear derailler?

Most highend bikes at the time were handmade to one degree or another, even production bikes. I do see a lot of file marks... perhaps the serial number was filed off the bottom bracket before those holes were drilled.

I have recently picked up a 72 Frejus like the CR one that has Legnano characteristics. The one on CR does not have a SN, mine does. I'm not sure how Frejus normally treats the BB shell, but mine has a slot.

Edit: my BB shell is solid, not slotted. That was another project I worked on this weekend.

Interesting. My back derailler was made from 1966 to 1973. I found that out on this site. https://www.campyonly.com/history/campy_timeline.html The one without a serial number, does it have the same frame joints as mine?

Meaning it has no date? They were dated at least until '84.

Strange that the rear derailleur wouldn't have date (late 60s?), and the front looks like it has the CPSC lip (mid or late 70s?).

Didn't the early Frejus (Freji?) have the serial numbers stamped into the side of the seat tube? Could be completely mistaken, as I'm going completely from memory.

No, the non SN Frejus, and mine (with a SN), actually look more like Legnanos, painted Legnano green and with the Legnano seat binder bolt. But Frejus decaled, and 531 tubing as opposed to the Legnano Falck. So Frejus isn't beyond making you scratch your head.

My reference point is with 1960's frejus frames. I ones that I have all have the serial number stamped on the seat tube. The bottom bracket is solid, not drilled and usually has the frame size marked (i.e. 58, 60, ect). With frejus frames, I look for the oiler ports on the head tube and bottom bracket along along with slots at the top of the seat post. Granted, my bikes are older - but I don't see any of these features in the OPs pictures. Granted, things may have changed in the 70's - but my (uneducated) guess is that it's just decaled as a frejus. The drilled bottom bracket shell is out of place. However, it's still a very pretty bike -