Rib profiles could be left as a scan of the original
somehow...although I don't have that large a scanner, but I have laid
out an airfoil profile before in AutoCAD using chord stations and
figures as listed in "Theory of Wing Sections". It seemed to
reproduce the airfoil faithfully. Such a method could be used here,
too, provided the type of airfoil is known.

Granted, my offer to help convert the plans to DXF files was shooting
from the hip. It would stand to reason that reproduction of the
drawings would have to be done with the utmost care.