The Secretary-class cutters underwent a tremendous amount of modification during their long careers, serving as ocean station ships, convoy escorts, amphibious force flagships, weather ships, and heaven knows what else. Some years ago, when I was working on a series of drawings of them for the CG Historian's Office, I had occasion to try to track down the details of what three of them - the Taney, Spencer, and Duane - looked like in three incarnations, before and during World War II. I was surprised to find how sketchy the actual, reliable documentation was. I can sympathize with anybody who has trouble sorting out the whole story of what all those ships looked like throughout their careers; I'm not sure anybody actually can.
I think the original Revell Campbell kit was intended to represent the ship as she appeared when the kit was released: in 1957. According to Dr. Graham's book, it was reissued under its original name in 1968, and as the Taney in 1976. (The book's coverage ends in 1979. The kit was issued at least once after that - in the "Special Subjects" series version that I've got. Revell used - and is using again - the name "Roger B. Taney." That was indeed the ship's original name, but the names of all but one of the ships in the class were officially shortened to just the last names in 1937. The exception was the Alexander Hamilton, which kept her first name in order to avoid confusion with the Navy destroyer Hamilton.) I don't have an original Campbell kit to make a comparison, but I'm pretty sure the parts have never been changed - except for the switch from multi-colored moldings to all white ones.
The actual Taney's appearance changed pretty dramatically at several points in her career. For a while, during the war, she had three 5" gunhouses and looked downright top-heavy. The instruction sheet for the version of the Taney kit that I have says it represents her as she looked during the Korean conflict. I'm not prepared to say that's incorrect - i.e., that she didn't at some point look essentially identical to how the Campbell looked in 1957. This page from the CG Historian's website contains a couple of shots that do look pretty much like the Revell kit does (i.e., with one 5" mount forward and a virtually bare afterdeck, except for the depth charge gear): http://www.uscg.mil/history/WEBCUTTERS/Taney_WPG37_Photos.asp . That page also confirms that she did wear the "Coast Guard Slash" on her bow for a while.
In other words, I can't assert absolutely that the Revell kit doesn't represent the ship reasonably accurately. (We're not talking here about a stunt on the level of a slightly-modified H.M.S. Bounty masquerading as H.M.S. Beagle, or the Cutty Sark impersonating the Thermopylae, or the Flying Cloud pretending to be the Stag Hound, or the Eagle disguised as the Seadler.) It's a decent kit - at least by the standards of 1957. My complaint is that the person responsible for writing the copy on the Revell website just plain didn't know anything about the ship - and didn't make any effort whatever to find out. (I was able to nail down the date when the Taney became a museum ship in less than five minutes' research time - without leaving my computer.)
The bottom line is that the U.S. Coast Guard is scandalously under-represented by the plastic kit industry, and we probably ought to be happy that this kit is coming back on the market. Gold Medal Models offers a set of photo-etched detail parts for it; with the help of that set it should be possible to turn it into a really impressive model. And it certainly offers scope for conversion. I don't know off the top of my head how many models it would take to represent all the ships in that class in all their configurations; I suspect it would take more than a dozen. To my eye, though, they looked best in their "as-built" configurations - with two open 5" mounts forward and the handling gear for a Grumman Duck or Curtiss Seagull aft: http://www.uscg.mil/history/plans/CGCRogerBTaneyColor.jpg .
Regarding the box art - my memory isn't good enough to comment intelligently. I do remember (I think) the painting that showed the Campell rescuing men from a foundering merchant ship, but that's all I can recall. I just took a look through the pictures in Dr. Graham's book; no luck. He does reproduce the painting of the Buckley ramming a U-boat - but that one, of course, is based on reality.