I am not aware of anyone who has the actual drawings. I am working on getting them myself. No guarantees, but we'll see what happens. I know a fellow or two in the UK who have made 1917 and 1917A1 dummies. One made his own jacket and did a nice job. I know that Lou makes his from specs he took off originals, without the benefit of arsenal drawings. He nailed it completely. They are incredibly nice. I can tell you that the tube diameter is 4 1/4 inch. Not easy stuff to find! And it is not available in the correct wall thickness so it has to be turned on the inside, the length of the tube. Have fun!
As to the rest of the 1917A1, the only items that are different from the A4 is the top cover fixed base (riveted on the otherwise standard cover) and rear sight, and the top cover latch. The cover and latch are available at Numrich or Sarco. Numrich has the lower price, but Sarco has NIW condition. You can get the sight moveable base and the windage screw assembly from Numrich, but condition will vary. Also, they have most of the combo slide parts, and you can make a ladder mock up if you like. Assuming that you do not wish to pay retail for one of my repro sights, I can tell you that I occasionally have ladders with defects that I can make available for a relatively low price. The defects relate to the depth or quality of the engraving. Let me know if that will help on your project.