The largest and most correctly detailed kit is the 1/350th. Minicraft Version, it's right at 30" long. Myself and several other modeler helped Minicraft make the needed corrections and inprovements on this kit back in 1992. I just finished another one for a client yesterday. I have some pictures in my webshots album, I'll up load the rest this week.
You can get the kit in two versions, with and without metal etched brass railings. These are provided for by Gold Metal Models. However, all you get are the railings kit with the plactic model. I usually also buy the full GMM set with gives you the following, crain hooks, boat davit rigging and others items.
Also if you buy one off ebay, make sure you get the UPDATED kit, ther are a ton of the wrong kits still out there. ou can email me direct if you want some pointers.
Jake