I cheated, I fabbed some brackets, bolted them to the calipers, pumped the handbrake so things would self center and hold itself in place, and squeezed the trigger on the welder.
Perfectly centered
The jetta and passat calipers (and Audi cabriolet in my case) are the same bits
the MOUNTS the calipers attach to are slightly different Jetta vs Passat/Audi cabriolet.
Addendum to Newtons first law:
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.