You have to consider that the scale of the original paper tables is absurd, like 1:1.35.
Of course I got the PDF by photographing the paper tables and the image is completely out of scale.
However, the correct measurements are those reported on the tables, so you can't go wrong in getting the necessary pieces.
The problem, if anything, is having the measurements that are not reported.
With the paper tables I didn't have any particular problems, for example I measured the mainmast which on the paper is not 445mm but a little less and so I got a scale ratio that I used to measure what I needed.
In your case it's a little more complicated because you don't have the paper tables. However, you can either use a software able to measure between two points of the PDF or print the PDFs in any format (better if A3) and then do as I did.