Thanks for the welcome
My vote went for Jared Padawhatsis, from Supernatural. Mainly because I thought he looked like the closest fit, visually. And in theory we'd have to start with a younger actor, otherwise I might've been tempted to go Olyphant... though I admit I wouldn't have thought of him without seeing him listed there. As far as Jared goes, I've never seen Supernatural so no idea what his acting's like, but I've heard great things about the show this past year so I assume he's up to snuff.
As far as Harry's features, in my mind at least, it's more his attitude, gumption and, world weariness that give him his rough looks (well that, and being a bit of a slob heh), and less any kind of Marlowesque chin-chiseling. Peter Parkerish, as I think I've seen Jim mention a few times elsewhere. Hence, Chuck heh. But I admit, I'd have to see Levi pull off the character in an audition before I was completely sold. I've only recently gotten into Chuck, and haven't seen him pull off any Harry-level badassery yet, so he'd have to convince me.
And if any of this were to actually happen, there's the fact that Levi's looking to break into movies in recurring, high profile roles as evidenced by his being in the Superman running recently. That, and he'd bring a hefty cult-following into our own cult hehe