You will sink it, but trade for it anyway!
I think you are way to heavy to really get any performance out of this boat and if you were to buy one I'd say don't do it. You seem to have a chance to trade a boat you don't use for one that will be a fun, flop around in the water, toy. So give it a try! You may get bored with constant rolling, ends, squirts, intentional and not. If so, you have a great new boat to trade or sell for something else.