A couple of comments. The trunnion support joint originally had small rubber bellows on both sides to shield the shift shaft & ball from slop, road grime & keep lube inside. They were regular neoprene and didn't last more than a couple of yrs. I haven't seen one on a Pantera in this century. Might be worth while fabricating some & gluing/clamping them on if you encounter such stuff on the road regularly.
If you have machining capabilities, heim balls are 8740-high-carbon steel but can be quickly cut oversize on a mill or lathe with a sharp cutter (NOT a drill!), slow speed, light cuts & plenty of lube. Skimp on any of those and the cut area will work-harden ahead of the cutter from heat and you just made junk. I haven't tried it but a small brake hone might open up a heim ball. I prefer a mill & carbide cutter. Remember to keep the ball cool while enlarging by any means!