I hope I may be forgiven for poking my nose in hear. I'd like to see some pictures of Kapudan's conversion too. On the basis of what he's posted before, it's clear that he knows what he's doing.
I can offer a little information about the Revell kits - with the help of Dr. Graham's fine book, Remembering Revell Model Kits. The Eagle/Seeadler/Gorch Fock story is interesting and a little complicated.
Back in 1958 Revell issued a 1/254-scale model of the U.S.C.G.C. Eagle. It was the fifth sailing ship kit the company produced (following the Constitution, Bounty, Santa Maria, and Flying Cloud). The odd scale was, of course, one of the notorious "fit the box" scales. (The first in the line, the Constitution, was on a standard scale: 1/192, or 1/16" = 1'. It looks to me like Revell designed the box to fit that kit - and thereby committed itself to a standard box size for the smaller sailing ship kits it released during the next fifteen years or so.) It was, by 1958 standards, a nice kit, with some remarkably fine detail. Unfortunately it was (at least I'm fairly certain of this; I haven't actually measured the kit) based on the widely-distributed plans by Harold Underhill.
Underhill was a fine draftsman and knew what he was doing. Those plans originally appeared in his book, Sail Training and Cadet Ships, as representing the whole class of training barques that were built by the German navy in the 1930s. The text of Underhill's book clearly says that all of those ships were, in fact, different in length, and explains equally clearly that the plans are those of the Gorch Fock. The Horst Wessel, which became the Eagle, was about twenty feet longer. Underhill knew that, and the U.S. Coast Guard knew it. Unfortunately, though, the plans got reproduced and sold through various outlets with the name Eagle on them. Virtually every Eagle kit has been based on them, and therefore is about twenty scale feet too short. (The one exception, as we established in a very interesting exchange in the Forum a few months back, is the no-longer-available 1/200 kit from Imai. That one is based on modern Coast Guard plans, and got the proportions just right.) On 1/254 scale, twenty feet works out to be about 15/16". It looks to me like the discrepancy is on the maindeck, between the aft end of the forecastle superstructure and the break of the quarterdeck. There should be considerably more open space there than the kit indicates.
So the original Revell kit represented a squished version of the Eagle as she looked in the late 1950s (quite a bit different than she looked when she was built - and a whole lot different than she looks now). I may be mistaken on this next point (maybe somebody who has the old kit can correct me), but I think the Eagle at that time had a pair of small saluting guns mounted on her forecastle deck, and these were included in the kit.
In 1960 the Revell Seeadler appeared. I'm basing the following on my highly-defective memory; be warned. I think the changes from the old Eagle were as follows: 1. The colors of the plastic were changed. (The Eagle had a white hull; the Seeadler's was grey.) 2. The mizzenmast was changed and a new set of yards for it was added, to change the rig from barque to full-rigged ship. 3. The big Coast Guard motor launches, with their fancy canopies, were replaced by open boats.
The big gap in my memory concerns whether the Seeadler had an engine or not. If not, the Eagle's propeller and the exhaust stack for the diesel engine must have been deleted - and the hull halves must have been modified to eliminate the provisions for the screw. I think I remember the Seeadler kit that way, but I'm not sure.
I think (I'm not sure) the only guns in the Seeadler kit were the old Eagle saluting guns, but I may be mistaken about that too. In any case, the biggest difference between the kits was the change from barque to ship rig.
I think the Gorch Fock in the current Revell Germany catalog is a reissue of the old Eagle. (I'm not sure about that. I've seen some photos of it, which certainly give that impression.) If so, EPinniger is right: it represents the original, pre-WWII Gorch Fock fairly accurately (more accurately than it represented the Eagle). Whether the old Gorch Fock ever had canopied boats like those I have no idea; since she was being operated by the Russians in the 1950s, I rather doubt it. I also don't know whether Revell bothered to to anything about the figurehead. (The Eagle's figurehead is a - well, never mind. I think the Gorch Fock's was an albatross. On 1/254 scale there wouldn't be a lot of difference.)
I haven't seen any of these kits for years; maybe some Forum member has at least one of them in hand and can correct me. Now, Kapudan - how about some pictures?