Hi JMAN!
I'm no butcher, but I think you have a "small" whole shoulder. I've never seen a butt that big and the fact they mention "blade" leads me to believe you have the whole shoulder...which includes the butt and the picnic.
I have cooked several whole shoulders and they usually weigh in around 12-15 pounds. Depending on the butcher, if he left it un-trimmed, there should be a rather heavy "fat cap"(actually the skin I believe) on part of it.
I would trim as much fat from the outside as possible....there is plenty of internal fat to keep it moist.
Regardless, cook to internal of 200�. Plan on around 2 hr. per pound...but remember.....it's done, when it's done!
Hope this helps.
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