Not sure if you can use the word "Kit" and Giant Scale, as in bigger than 60 inches, in the same request. That is pretty much scratch built territory. 'Been there' and still in the process of 'Doing that'. Just find the plans that you like of a smaller kit built model and take it to Kinko Copy Center and blow it up to any scale you want. That is what I did. Kinko can only go 48 inches wide on their printer so you might have to tape together some pages if you want to be able to sit in it after you build it and launch it.
Oh one other thing. The price of every component is also large scale and the availability of parts, to scale, diminishes exponentially. At some point your hobby store becomes the West Marine Store (Theft Marine) and then your price of accessories grows exponentially. If you have every owned a big boat (>25 feet) you know what I mean.
My [link=http://www.rcuniverse.com/forum/m_3993444/mpage_12/key_/tm.htm]72 inch Harbor Tug[/link] is already past $3500 and my[link=http://www.rcuniverse.com/forum/m_9713018/mpage_2/key_/tm.htm] 76 inch Shelly Foss [/link]is half way there without the electronics installed yet. Neither one of them I can ride in but my cat could. The look on my neighbors faces when they see that harbor tug pass in front of their docks is absolutely priceless. Great way to be neighborly and transport a half rack down to a party on someone's dock. That was my vision for building them in the first place.
As for making ballast that is another story. You have no idea how much weight you will have to carry around to put one of these large scales down to the water line. I am already up to three deep cell blue top optima batteries at 44 lbs a piece and still not down to waterline at $155 a piece. Can't put the wieght in the boat before you launch it or you will have a bad back in no time so you need to have and efficient way to put weight in it at the waters edge...hence forth the batteries come with good handles and they give you about 190 hours of play time between recharges. Might as well install an inverter and use real 200,000 candle power spot lights and a compressor to run your fog horn. Everything is way out of scale when you are talking large scale.
All I can say is I am having so much fun building these tugs and even more fun running the 85 foot tug on the water already. I am wanting to build the 14:1 scale version of the crowley invader class tug. The problem is that it would be 9 feet long to be the same scale as my other two tugs. Given that it is suppose to be faster than the Shelly Foss, I will have to put pretty good size power plants in it. Well it is not much of a problem except that it will be darn near impossible to take it anywhere. The good thing is that most of the parts are available at West Marine.
Opps I got out of scale on that reply