Check out the Steeler's 2010 Defensive 2-deep. Hood and McClendon at LDE; Keisel and Eason at RDE. Weights are 300, 280, 285, and 305 respectively.
Speed isn't nearly as important as strength and size for a 3-4 DE (which is why they're usually converted DTs). A 3-4 DE doesn't attack the OL and try to penetrate; he engages, holds his ground, reads the play, and flows to the ball. If he's too light, he'll have a hard time holding his ground, thereby opening running lanes. If he's not strong enough, he'll have a hard time swimming through OL to make a tackle once he reads the play.
Aaron is a prototypical 4-3 WDE. He'd almost certainly start as a freshman on any 4-3 team in the country. But a 3-4 DE requires a different skillset and build altogether; consequently, I doubt Aaron will challenge for the #1 WDE this season. How Longo ultimately shapes his body will be very interesting.