I know that I am getting waaaay ahead here, but if you were ever going to desecrate what is already looking like an excellent model by weathering it, the AM3s (lets use the correct classification for the era) suffered from an unusual and I think unique weathering, - the body sides would get a covering of a horrible dirty yellow film which used to obscure the windows! The cause of this was traced to a combination of the chemicals used in the carriage washer at Bridgeton and the dust that was generated from the brake shoes fitted to the units, apparently it was very difficult to remove once it formed but this lasted for a few years around the late 1960s/early 1970s.
Jim