Try Safety Devices for a roll cage . I've got one from them for my 190 C36 manual .
A couple of my mates and I bought a cheap as chips 190 2.6 manual , and we have stripped the whole thing , sunroof and all ...... it's incredible just how much everything weighs ... try getting a set of Toliman wheels too they are half the weight of most M-B wheels - that's 40kg's saved right there . Be absolutely brutal when stripping , but keep the heater for demisting purposes . try to change the electric windows for manuals , maybe get some plastic windows ?
The bumper irons weigh tons too , just cut them either side of the brackets .
more later ....