Ian,
So long ago, but from memory Ford supplied three pivot blocks which fitted the Weber butterfly operating arms. The blocks were simply linked by a threaded 2 BA rod and synchronisation was easy by moving the blocks along the rod and then locking them in place with 2 BA nuts. I think the throttle cable was linked on the No. 2 carburetter. However all your queries would be answered if you could lay hands on my ME file which I included when I sold '169 . Maybe the file is still with the car ? Worth asking the owner. All sorts of details were in it including the shorty exhaust manifolds, Hyvo chain set up, gearbox uprate and heated screen wiring. Never a good idea to reinvent the wheel.
Incidentally the main function of the triple 42DCNF set up was to look good. Yes it did provide a little performance, but only at excessive (for a road car) RPM. For what my opinion is worth the 500 cfm two barrel Holley was a far better bet and I would have changed to that had I kept the machine. Finally I would warn that the transmission will not last more than 10K miles at much over 150 bhp and you can easily make this with the standard 38 DGAS Weber.
Barrie