I think Johnson went for 65 and a TD against the Stillers last year, which is not too bad and he'll certainly catch a few passes. Reggie Bush won't rush for any more yards, but he will catch some passes, which, in my opinion eves the two out. So, all things constant, I would start Chris Johnson regardless.
10 man non-ppr (Bush League)
QB: Romo, A. Smith
RB: Foster, McFadden, Doug Martin, Donald Brown, Ben Tate, Rashard Jennings
WR: Roddy White, Brandon Lloyd, Titus Young, Harvin