I am curious too see how accurate the ZAC pieces are compared to the drawings. I would not immediately conclude that any difference was an error on the part of ZAC. There may be good reasons for the ZAC pieces to have different measures compared to the drawings. I am a first time builder so I view this comparison as an ongoing opportunity to learn from the ZAC kit.
So far while building the rudder, I found one discrepancy. Rear Rib #1 (65-T-4-6) should have a 57° bend to its flange at its forward end. The ZAC produced part measured 60°.