I think I'd run track down the outside of the shed, just like you have done there. It would be usual to see a loco parked along side a shed in real life, again just like you've done there. Also, the extra track would be useful to have when shunting or moving locos around. You could always run something into it out of the way.
Looking at the pics, the 201's seem to fit fine under the shed as it is. If you intend to put a concrete floor in, I'd put the concrete between the tracks as opposed to putting the track on top of the concrete floor. That would keep the height down, and be more realistic too.