I haven't looked too deep into on any tipoffs on game plan for the Skins, but Cravens would be interesting and preferred after his 60 snaps last Sunday, in terms of talent and better big play ability. I could see them use him to shadow Dak, kinda like they did at times against Rodgers last week. Plus, you know the Cowboys will sustain drives and pound the rock that is really good for linebackers and those that play close to the line. We saw John Norton touting both Ravens linebackers last week against Dallas as strong matchups, and I don't see any reason that Cravens wouldn't stand as a great matchup.
As for Whitehead he's had a solid "fantasy season" because of opportunity. There has been talk that Levy might play, but I don't really trust the Vikings to sustain drives or stick with the run with regularity. I'm sure you know but that's not a script you love for linebackers most of the time. At least I don't.
I'd role with Cravens if you play for a higher production this week. If you just need steady points to win, just go with Whitehead. Cravens has big play potential but if they go away from him in the game plan, he could to very little for you.