For Reece, you gotta wait until Sunday morning, and see what the injury report says about Mcfadden. If he's out, then definitely Reece. Now, if you have to choose between Danario Alexander and Mike Wallace, I'd go with Danario. Pittsburg QB situation is a mess right now, at least Philip Rivers is known to throw the ball to Danario.
Now, if McFadden does start, I'd say go with Blackmon in that flex.
I've got a similar, albeit more complicated, Reece/Blackmon dilemma too, if you wouldn't mind:viewtopic.php?t=530734