Hi,
I can not say specifically on these drawings.
When I worked for a civil engineering company c1973-4, I got the photo lab fellow to take the Model Railroader issues on the K27s and put them on the vaccumm table. He took a photo and then I was able to make blue prints from the photo paper.
It looked original and period except that MODEL RAILROADER was on the drawing pages.
During the era, computers were expensive and building sized machines. The forerunner of the PC was room sized.
I'd say to ask for verification that these are originals and not prints from copies of the originals.
Doug vV