I used a kit to replace everything under the hood that holds or passes refrigerant, then restored everything in the cab myself, replacing the parts that were beyond fixing. The evaporator case had a poor attempt at professional restoration done, and I had to follow up and finish the job on that myself. I am pleased how it turned out. I would get A/C going again on another truck the same way, except I would not send the evaporator case to somebody else, I would just do that part myself. Here is my thread on the subject.
https://www.67-72chevytrucks.com/vbo...d.php?t=790246