I have my 1520 mounted in the front/upper position on the dual motor mount, traxxas front swaybar clears with no issue. It won't fit in the rear/lower position. If I remember correctly, in the lower/rear position the 1520 extends past the rear shock mounting screws, so even a short shock mount won't help. The 1520 is fun as hell on 6s, but the front/upper mounting position doesn't help handling. Body roll is ok for bashing, but there's too much weight up front. Transitioning between under and over steer is not very predictable. And the stock motor wires barely make it to the esc.
Edit: added pics and measured my 1520. The red arrow indicates where the 1520 would end up in the chassis. Almost touching the shock screws. Maybe if the mount was aluminum you could shave enough down and maintain strength, but only if the motor mount was shaved down to move the motor forward too.
