If you have a specific brand in mind, call the manufacturers and explain your situation, they may have a recommendation or solution for you. If you're in Brazil, go to the store or factory you can get it tailored right there, just like buying a suit. Another option is to check out some of the judogi as this is a larger sport with more "plus-sized" competitors (see Judoinfo.com). Lastly, many of the folks not within the mold of the kimono companies simply buy a larger kimono and then get it tailored locally.
One e-mail I got recommends Atama: I'm 6'8" 285 lbs and got a A-6 Atama single as recommended by my instructor. I can't really compare it to anything else since it's my first gi, but it seems to be holding up just fine considering my weight. No damage to report except for one of the embroidered letters came out. As far as the coat goes I'm willing to say that an A-6 coat would fit up to 6'10" and probably about 325 lbs. Coat is enormous. Although sleeves might be starting to get to short. Pants are also big boy size and when I got them they touched the floor standing. Now they have shrunk to right at my ankle. Overall very pleased.