It looks like both the CC and MTL cars are based on the same prototype, and have the same doors, so that probably won't matter. The MT car seems to be a little taller, even without the roofwalk, so it might be the better choice there. The CC car is supposed to be a plate C car, but is closer to plate B in height.
Another oddity is that they both have diagonal panel roofs, but the diagonal panels go in opposite directions. Were the prototypes for both, or is the CC roof backwards? The MTL roof matches all of the other diagonal panel roofs I've seen.
With all of that, if you can get the CC car easily and at a good price, it would be a good starting point.