My son took a very large mature Shiras in 2014, hanging at the processor it weighted 667 lbs on their scale. We got over 400lbs boned out meat as I recall. It filled three large coolers once cut wrapped and frozen. About 30% larger than elk sounds about right. With the head, hide and guts, I bet it was well over 1,000lbs. We did not weigh all the parts, but 1,200lbs would be in the ball park I suspect. We saw several Moose, likely younger Bulls, that were much smaller. So just like elk the size will vary.
I've seen quite a few of the AK/Yukon variety that made this one look tiny, as in about 60% larger. I have a picture of his Shiras gutted and hoisted by a front end loader, just before we put him in a trailer, I just shake my head. They are big, the size of even an average Shiras Moose is huge.