Hoping someone can help me ID this headset and bottom bracket from an early-80s Vitus 979. Which gruppo are the from? I don't recognize the square headset at all

Not much of a Campophile but I think that headset went with the Delta brakes or the record brakes with the blue jewel in the pivot bolt. And that looks like someones home made spacer.

Hard to tell but the Record had alloy cups those look like steel -- which would make them Athena, Chorus or even Croce' de Aune'

Athena.

Athena.
That's what I thought too, but Athena had "Athena" engraved around the edges (see attached pic). This one just says "Campagnolo-Brev-Int."

IIRC, only Record parts had the Selform technology - the steel race was on a block of black polymer that allowed some give in the structure, reducing the fretting problem (often incorrectly referred to as brinneling). The BB cups look steel, but they have the same cut as Record, so if they are aluminum . . . The HS does look like Record, but if there is no black polymer under the bearing race, then not likely.

IIRC, only Record parts had the Selform technology - the steel race was on a block of black polymer that allowed some give in the structure, reducing the fretting problem (often incorrectly referred to as brinneling). The BB cups look steel, but they have the same cut as Record, so if they are aluminum . . . The HS does look like Record, but if there is no black polymer under the bearing race, then not likely.
I've hunted around for awhile and found a number of photos of C-Record headsets for sale, and as far as I can tell they're the only ones with this distinctive shape and shoulder?