True 27's will probably rub on the new wheel well protection added to the 520's before it'll rub frame, it'll be close. Going with 14" wheels is fine other than it'll ride a little rougher, having less sidewall cushion. If you go up you'll want to spread the stance, 50" goes out the window or it's a puckerfest. Steering isn't an issue, you'll just have to muscle it a little more and bump steer will be worse.