Probably bad form to reply to my own post but I thought there would have been more response.
Anyway, I was googling some differnt combinations of w123 and amg and found a few pictures, including what looked like a scanned amg brochure with a 280E and 280CE. Unfortuanately, the writing was in French (I think) but I did recognise one number 185, which was closely followed by another number, 225.
I'm guessing they raised the stock horsepower from 185 up to 225.
Yeah, have a look at the http://www.w123-world.org/ Theres a guy who has a coup that has just had a V8 transplant and he has all the AMG kit. Im fairly sure no manifold was made by amg, although I think there was an AMG or Brabus non-v8 lump... Sorry no one replied to your posts, these forums are pretty slow!