( warning: long rambling BB58 style statement on shoulder issues with BMBH)
Chester, this is kind of a tough question to answer, pretty much ditto what Brian said. The official upper weight limit of the BMBH is 250 lbs, having been lowered from the original rating of 275. So you are kind of pushing that, but I really don't think there would be any problem. I think the bars determine the weight rating, and I think there is some reserve built in.
But as for your really wide shoulders. 1st, some folks here have simply not been able to be happy with the shoulder room. I was that way at 1st also, but I changed my mind over time and really don't find shoulder room to be a big enough problem to stop me( 6'1", 212) from enjoying the other benefits and getting a good night's sleep, even flat on my back. But I think you will notice the shoulder "difference" regardless of your size. My 120 lb wife noticed it! If you look at the BMBH unoccupied hammock from the ends, you will notice a "U" shape, or maybe approaching a "V". This pic has the MW3 on, and that may alter things slightly, but you still get the idea:
( OT, but notice the perfect fit of that quilt to this hammock! )
At it's widest
(unoccupied) point, this hammock is ~ 28"(the bars are ~31"). Down inside the hammock close to the bottom, more like about 22".
My shoulders measure ~ 20" wide across the front of my chest, at elbows more like 23". If I curve my shoulders forward slightly( think bad posture) it is ~ 19" outside shoulder to shoulder. But regardless of shoulder width, when you sink down into this hammock, it is going to try to force your torso into the shape and size of the hammock. The amount it can come in on you is limited by the bars at the top, but in effect it will hug your torso, and have enough inward pressure to cause your shoulders to "curve".
But this is not the same to me as traditional "shoulder squeeze" like I get in a gathered end hammock hung to tight. This hammock is more or less forced into the shape of your torso, and the curves upward towards the spreader bars from there. It is this curve which your shoulders will conform to. If your shoulders are wider than mine, they will just continue assuming that gradual curve shape of the hammock further up. The closer to the spreader bar your wide shoulder get, the wider the hammock is, all on a constant "curve".
This is my theory on why my wife, who weighs 90 lb less than me and is probably "petite", and whose shoulders are 3 or 4" more narrow than mine, felt the same shoulder limitations as I did. I think every body feels it. But if I just fold my arms across my torso, I just don't find it to be an issue. It is not squeeze, it is just that my shoulders, now with a very slight curve to them(exactly as you have if you place your arms as above) are just lightly contacting the hammock sides. And of course, shifting even very very slightly to my side ends that issue.
But if anyone lays down in this hammock flat on their back arms by side, you will quickly notice the lack of room, and I guess that bothers some too much. In fact it bothers me, but I don't sleep with my arms like that in my bed, so I don't care. If my arms are over my torso, it does not feel much different in my bed.
You won't know if you can put up with that unless you try it, but I thought you ought to know what to expect. Wider bars would cure this problem, but spreader bars already are a problem (solvable though) hitting tarps, and wider bars will just be more problem. Also, you can only draw your knees up a moderate amount. What is virtually guaranteed in a bridge is no issues with knees or leg pressure, and no side "twisting" issues.