RE: Grumman Widgeon
I tried enlarging the Paul Matt Drawing, but the lines also got enlarged, and they appeared very wide and fuzzy on the blowup, to the extent that one could not be sure exactly where to measure from. Perhaps your software somehow digitizes the lines, (you mentioned vectors), so that they remain a reasonable width when the remainder of the drawing is enlarged.
Incidently, the original Paul Matt drawing was 1/24 scale, or 1/2 inch to the foot. It was two large 16 x 22 sheets. In the magazine article and the Historical Aviation Album, it was reduced to 1/48 scale, or 1/4 inch to the foot, so it could fit on two 8-1/2 x 11 inch sheets. I hope that you are getting the larger one. I still had to enlarge the larger version six times to get quarter scale, which is 3 inches per foot. So the lines became six times as wide. for full scale, I would have had to enlarge it 24 times.
Al Franklin used a projector to shine the enlarged image on a large sheet of paper on a wall. He then traced the image onto the paper.