The engines possibly breaking up is certainly a valid issue. The CAB report said that in only one case did they fail to get torquemeter readings from an engine, which suggests that only one engine broke apart at the drive shaft. One newspaper article mentioned that the investigators were surprised at how well the engines held together.
They mapped the site, of course, and all that documentation existed once. But when the CAB moved their records to the FAA all that was discarded. There's nothing in the National Archives and I haven't been able to turn up anything else. If I had a debris map all this would be easily settled. That's what makes this a detective story.
The energy of an engine hitting the embankment is one of the things I've wrestled with. I've tried to find experienced crash investigators to give me some feedback, but haven't found any yet. I go into that at some length in my document, but it's all guesswork.
You're right about the photographer getting that shot if he could. That plus the Bridgeport Post article suggests that whatever was on the track was moved really quickly. Something was there in the aerial view, but not when he was at the tracks. I have a faint hope of hearing more from the Chicago & Northwestern Historical Society, which maintains a lot of unsorted old journals and records, but their first response was not encouraging.