Adding 3lbs of LME will increase the beer's sweetness, make it feel heavier, and increase the alcohol content by close to 50%.
For this beer I would probably go with Safale US-04. But you know what? I also might grab Safbrew T-58, which is a specialty dry yeast that leaves a spicy, peppery taste. Or maybe a blend of the two - there's nothing wrong with using two packs of yeast, so why not try them both in this beer?