The water jet left me a nice insert piece that is the correct port shape:
I decided to make a forming tool from it. I reduced the profile by about .050" to account for the tubing diameter, and rounded the edge where it will go into the tube. Sanded and polished the edge to keep it from grabbing, drilled a hole and added a handle:
I formed the tube with the tool, slid it into the flange, and formed it again:
