Look at the Chippewa Wedge-Loc treestands. Get the phone number off the website and call the guy who builds them (he and his wife own the co.) and asked him any questions you might have. They are not cheap, but they are very solid and well made. I own the lighter models, but I know 'The Brute' has a 400 lb. wgt limit and I think they have one with a bit higher limit.
http://www.chippewawedgeloc.com/
TB