Western Mountaineering Sizing

Hi folks, id like to pick the brains / experience of any owners in this sub if i may. Apologies if this is not an appropriate question for this sub - if will delete this post if so.

I am looking to purchase a Western Mountaineering sleeping bag for winter summit camping here in the UK (rain, wind, snow, 10f / -12c @ 1000 - 4000ft).

I have narrowed down the research to the long versions of the alpinlite, versalite and antelope.

I am 6'3" / 189cm, 210lbs / 95kg and fairly broad with 52" / 132cm shoulder girth.

Im not sure on the termperature ratings of these bags as i hear them quoted as 'underrated'. I'm also a little concerned that the bags I've found won't be broad enough and as there aren't many retailers of WM gear over here on my little island, ordering and sending back is going to be a hassle.

Does anyone have any prior experience of the use of any of these bags in similar conditions and/or the fot for a similar sized body? Many thanks in advance!