Here's a good review of the Revell Alabama and Kearsarge kits: http://www.steelnavy.com/Alabama&Kearsarge.htm .
On the basis of my own recollections (which are pretty stale now), I have to agree with Mr. LaBow. The Kearsarge kit represented a state-of-the-art attempt to produce a scale model, the big flaw being the designers' failure to "backdate" the plans they were looking at to the ship's 1864 configuration in some respects while "backdating" them in others. It's certainly one of the best kits of its era.
The Alabama kit was largely an effort to recycle parts from the Kearsarge into another product. Note Mr. LaBow's observation that the hull halves of the two kits fit together precisely. (He also makes the interesting suggestion that the Alabama hull might make a better starting point for an 1864-configured Kearsarge.) Dozens of other parts from the two kits are interchangeable.
Revell did, in 1961 (or, more likely, 1959 or 1960; it presumably took a long time to produce the two kits), have an excellent excuse for making mistakes of accuracy in its Alabama kit. At that time little was known about the actual ship - so little, in fact, that it would have been difficult to establish that any features of the Revell kit (except the 11-foot discrepancy in the length of the hull) were actually mistakes. Since that time a surprising amount of additional information about the Alabama has come to light - including two contemporary models (one of which showed up at the museum where I used to work) and several previously unknown photographs (including a couple of outboard shots showing the whole ship). The book C.S.S. Alabama: Anatomy of a Confederate Raider ( http://search.barnesandnoble.com/booksearch/results.asp?WRD=Andrew+Bowcock ) contains an excellent survey of the available information (as of a couple of years ago), along with a set of reconstructed plans that would be excellent for building a model. Unfortunately the book appears to be out of print at the moment, but it's really a "must-read" for anybody trying to reconstruct this ship accurately.
The wreck of the Alabama was discovered a few years ago, and has undergone study by underwater archaeologists (including a couple from the joint where I work). The few artifacts brought up so far, though, don't really have much to offer modelers.
It would, of course, be unfair to criticize Revell for failing to take all this recently-uncovered material into consideration when it designed that kit almost fifty years ago. (There's a sobering thought: the total elapsed time since the start of the American Civil War has increased by almost fifty percent since those kits were released.) I'm not prepared to put that Alabama kit in the same category as the Revell "Beagle," which I regard as one of the more reprehensible examples of deceptive marketing in the history of the scale model kit industry. In the eyes of a knowledgeable Civil War naval history buff of 1961, the Alabama kit, carefully built, would have looked about as much like the real ship as could reasonably have been expected.
My parents bought me the two kits the next year - the Alabama for my twelfth birthday and the Kearsarge for Christmas. (The Alabama retailed for $12.00 and the Kearsarge for $10.00; that made them, along with the Revell Cutty Sark and Thermopylae, just about the most expensive plastic kits on the market. But Lazarus's department store discounted them a little.) I hate to think what they looked like when I got done with them, but the family and my friends were quite impressed. I remember proudly carrying them to school shortly after Christmas for show-and-tell. One of the other members of my sixth grade class - a girl who presumably knew next to nothing about ships or modeling - asked, "Why do they look almost alike?" And they certainly did. In reality the two ships did resemble each other a great deal from a distance. But not as much as the Revell kits.
My earlier comments on quality control in the recent Revell Germany reissue were, as I noted in that post, based entirely on other people's experiences. Here's an example: /forums/602912/ShowPost.aspx . It sounds like the individual kits from that reissue vary a great deal; I guess that's to be expected.
Maybe the bottom line in this discussion is the same one we've agreed on in several other recent threads: both these kits were excellent products for their time and, though they don't come up to the 2008 standards of the plastic kit industry, given the dearth of such kits we might as well be thankful that they're available at all - to the extent that they are. (Both kits are currently gone from the catalogs of both U.S. Revell and Revell Europe.)