The 64 Falcon v8 likely has same size tie rods as 75-80 Granada, which are quite a bit larger than the 68 Fairlane spindles. I know this is true for 63 V8 Falcon, so check the tie rods. We have adapters to go from small tie rods to larger hole spindles but not to put a huge tie rod in a smaller hole!

Also, the Fairlane spindles are same as 67-69 Mustang spindles.  They will bolt up to the ball joints, but the ackerman angle (refers to the direction the radius arms are pointed) is a little different and will cause bump steer.
There are other options that will bolt late model, better, disc brakes directly to the Falcon V8 spindles. What size wheels will be utilized on the Falcon.

While the spindle swap you are considering has been done in the past many times with ok results, I would recommend a swap that uses the original spindles. A set of 65-67 Mustang or Fairlane discs will bolt right on. An MS swap setup will work if using larger wheels.

If running 16” wheels, consider a swap utilizing 2005-2009 Mustang V6 11.2” brakes. They are very plentiful in salvage yards for cheap, the calipers rarely need rebuilding, you already have the v8 drum hubs needed, and the GT2008-FT MustangSteve brackets are now designed to work with the 11.2” brakes.  These bolt up to the Falcon v8 spindles and drum hub.
These late model brakes are much improved and use twin piston alloy calipers and are much better brakes than the 68-73 brakes like the Fairlane had.
If your wheels are 16” Torque Thrust II, you need to verify the spokes will clear. If Torque Thrust D version or M version, they should be ok. But still... verify.