Finally I got hold of the sources for the PDP-11 SPACE WAR that was submitted to DECUS by Bill Seiler.
The format is scans of the PAL-11S listing output. It is easy to crop the image to only contain actual source. Then running OCR on it. Tried a few online versions and tesseract. The problem is that the paper that the listing is printed on has lines. Very black lines. It makes the OCR go completely crazy. Source lines without black lines OCR ok. The others do not. The files need massive amount of manual intervention. Does anyone have an idea how to process files like this? A good way to remove the black lines? There are only 19 source files with three or four pages each so I don't think it makes sense to try to train tesseract to do it (training tesseract seems to be a huge undertaking). https://i.imgur.com/dvY973s.png /Mattis