Accelerator pump link on a 1405/1406 goes in the center hole.
Super simple carb for the average guy ---
7/16 float level, 15/16 float drop. Follow the IB for the proper jets, rods and springs. You do have to read it a couple times for it to make sense. This is the first of 2 1405's (one with the choke option) I rebuilt last week - the other and still cruddy(!!) is behind it:
Timing should be no more then 10* BTDC
Ford OEM distributors only run on ported
vacuum - pass side port on a 1405/6. Cap the other small one off or if you have a C4, run that line to the transmission
The front big vacuum port is for the PCV, rear for power brakes.
This photo shows #1, and the distributor rotates CCW as you look down on it (this is an HO wired dist, but #1 stays in the same place either way)
Get a vacuum gauge on that engine. If it has a stock camshaft, it will run 17-21 inches (mine is 17-18 with a medium warm camshaft)
Unless you understand pedestal mount rocker arms, don't disassemble until you do - they can and WILL cause you to suffer acid reflux