Well, it think it will not work for long, because of the torque. The Crossfire MT can handle a max. of 400 Nm. If you go over this number it's only a matter of time till it breaks. The Kleemann 3.7 has 525 Nm. So i wouldn't recommend a combination with a MT. The NAG 722.6 AT transmission can handle up to 900 Nm (when it's modified) and 560 Nm if you modify the W5A330 to W5A560 SRT6 standards . If you combine that with a AMG speed shift TCU and paddles, you'll have a much better fast shifting and durable solution.

Regards
Markus