I was going to suggest a trip over to
www.classicrendezvous.com for some history but, strangely enough, among the Italian marques there's no entry for Daccordi.
But here's what I do know. In the '80's at least one top echelon Euro Pro team were on Daccordis [I don't have my dogeared copies of Winning or my Visions of Cycling books handy so I can't tell you which one(s)]. But I can offer the following.
I have a Bertoni TSX which was made by Daccordi. How do I know this? Well, the owner of our LBS is the brother-in-law of the late Ben Lawee, the creator of Bertoni (as well as Italvega and Univega.) With the success of Univega in the '80's, Ben went back to his love affair with all things Italian and "created" Bertoni (no, there's no little wizzened Italian named "Bertoni" with a torch in one hand, brazing rod in the other and a cigarette dangling from his lower lip.)
Over the course of the Bertoni "brand", frames were made by Bianchi (most of the Columbus Cromor and SL "workmanlike" models), some by Rossin, and the top of the line SLX and TSX models by Daccordi. The TSX I have was personally "specced" by Ben, primarily the paint, the pantographing, and the webbed lugs. A friend of mine has an SLX with the same seat lug and bottom bracket shell, but minus the webbed lugs. He had it built up with NOS Campy Record C about 9 years ago.
I couldn't let the one I have go, so despite needing another bike like the proverbial hole in the head, I bought it (it had been hanging from the ceiling of our shop for something like 15 years) and built it up with Campy Centaur 10, all alloy, no carbon, no black bits. The finish work is simply better than most Italian frames of the same era, and easily the match of the best from De Rosa or Colnago. I've had it built for almost a year and have roughly 2000 miles on it. It definitely has "stage race" geometry - slacker seat and head tube angles than my other road bikes. But supposedly that was the intended purpose for the TSX tubeset. It rides and handles beautifully and would probably be my first choice out of my stable for a hilly (not brutal climbing - after all I'm old and it has a 39x25 low gear) Century. I love this bike and in 4 decades of cycling, I've ridden a few.
Interestingly enough, a poster in the fixed forum from Britain has a Daccordi with the identical paint, pantographing, and lugs but made with SLX, not TSX. It was called the "Griffe" (Italian for claws for the webbed headtube lugs). It's simply my frame but with Daccordi everywhere mine is branded Bertoni.
The frameset you are interested in has a bottom bracket shell identical to both my TSX and my compadre's SLX. The dropouts and the fork also appear to be the same. The seat cluster is more "traditional" than mine and the SLX. They are more of an investment cast "fastback" style.
Ben died of cancer in the early '90's (after being diagnosed in the '70's and given but a short time to live.) He was the importer for Motobecane in the '70's and sold off the business then. When cancer didn't kill him he started Italvega in his garage in Long Beach, CA, and the rest is history.
Bottom line, that Daccordi is as good as anything out there from that era and probably better than most.
Here's my "Daccordi" in a Bertoni disguise.