RE: Goldberg Ultimate 10-300 build
You may have trouble threading the rods. The factory threads on metal control rods are "rolled", which raises the threaded area higher than the diameter of the rod. If you try to cut your own threads, they will not be as high (as deep a bite) as needed. Get out the soldering iron and be done with it.. BTW, if you don't already have the solder clevises, you may be able to use the threaded ones to solder with. If they are too tight to slip on, drill out same dia as rod.
The other option is to use carbon rods with glue in titanium ends. Then you can use the ball ends you mention.