The rearsets I used (Old School Speed) came with swivel links and threaded rod. They are nice quality, perhaps not as heavy duty as I would have liked, but a pretty complete kit. I could have just used all the hardware included, but I wanted true heim joints and a polished aluminum link tube vs a threaded rod for the linkage so.........
I sourced 3 heims, 3 stainless allen bolts, 3 stop nuts, 3 long bolts, and 2 heavy thick washers for mounting the rearsets and connecting it all (along with that sacrificial exacto knife)
Then there is a 9/16" collar, a 1/4-20 female and male heim joints for the shaft connections (I re-used the original shifter linkage bolts to bolt it all together), a cotter pin, and a washer to complete the brake shaft and shift shaft connection.
2 small welding operations (the brake rod arm and the washer on the frame shaft mount bore)
Some simple bending and hacksawing (the brake stop and light actuator, the brake arm piece, and some bashing with a hammer and viola! Right side shift rearsets for about $250 and a little bit of work....and no opening of the gearbox.
Just one mans way of winging it, certainly not the only way, or the best, but it's here for anyone who wonders what it might take to do something similar.