I went to that web site as I am going to have to make my own 3 pt. too. I made the last two for my cub and an old montgomery ward hydro. I have the pdf file for the case 446 3pt and also a cad file. Attached is a file someone created based on his hitch. Hope it helps. I have compared some of the dimensions to those on my father in law's 3pt and so far so good.
In the past I went to the junk yard and purchased forklift valves and cylinders with hoses to build a very strong 3 point for my 2082 Cub. I have since sold the tractor and really miss that hitch.
Best of luck,