If "Ezeneli" knowledge is correct, and the Euro C280 and C36 shared the same tranny, then it would make sense it is spec'd for 320HP, since the C36 made 280HP and MB usually has a safety margin in the drivelines.

The M103 and M104 share the same tranny bolt-pattern so it should work for a M103-powered vehicle, however, it might be cheaper to find a 300E manual donor car.

:-) neil