Build the mounts and drop in the engine and gearbox first. You will have to use block huggers or custom-made headers as the steering gear is right under the master cylinder IN THE WAY.

The 123 chassis diff should handle the torque, it's the same as in a 126, which was offered with a 5.6 liter V8 (560 SE or 560 SEL). Plus, it's an independent rear, so handling is better.

The driveshaft is easy, use a Ford Mustang shaft, cut to length, change the front U joint and yoke to fit your trans. In the rear, redrill the pattern to fit a steel plate that adapts the Mustang flange to the three-point flange that the stock flex-disc bolts to. You must fabricate the plate.

Any more questions, ask a qualified Mercedes-Benz Master Tech...ME!