I built a wishbone today for a customer in Texas. Just built to his specs.
I first welded the 3/4" threaded bung into some 1.5" tube and plug welded it. I then sleeved it with a piece of 1.75" tube, with one end notched for more surface area, and welded them together. I also welded a 3/4" billet steel stud to a Ballistic pivot joint (big).
I then built the rest of the wishbone around that.
And the overall piece.