Rick raised an interesting question regarding the replacement of oem steering components with R& P.
In the OEM 'ball screw' system, the pitman arm and idler arm work on opposite frame rails to traverse a common 'back (or counter) shaft'. That is their only purpose in life. There isn't much geometry at play even though they turn in an arc.
This countershaft has tie rods. on both ends that connect to the spindles. So as spindles go up and down, so do the tie rods.
The real geometry is in those spindle forgings. Yes, they hold ball joints which allow the wheel to go up and down with suspension but equally as important, they have a trailing arm, set to a specific length and at a specific angle. This angle matches the wheelbase so that turning changes the radius of both wheels. Consider the difference in angle of both front wheels:
All this greek has been worked out by Ford when they manufactured your spindles.
Since Rack and Pinion only replaces that countershaft that traverses left and right, your geometry does NOT change.
Another important question is, how heavy-duty does your steering components need to be? I'm using a small Chevy rack gear in our Galaxie. BTW, my '59 Galaxie spindles are the exact same part number as Squarebird spindles.
Since the rack gear replaces and REDUCES the number of steering connections and joints, it feels much more solid. The rack gear is also in direct alignment with the spindles so it can be 'less beefy', let's say. The steering system only guides, which doesn't require much power.
Put it all together; no slave cylinder, no directional valve, fewer joints, more directly in line, less massive components, then you realize a manual R&P gear will work just fine. A power R&P system using any modern pump makes steering effortless in any parking lot. I'm using a pump from my Mustang GT. Works great and never any leaks.
Since Squarebirds (and Galaxies) didn't have R&P systems back in the day, a little fabrication needs to happen. I re-used the frame holes my steering box and idler arm used to populate for brackets that hold my new rack gear. I also CUT my steering shaft and ground two flats on the end to form a "double-D". I made a nylon 2" bushing for the steering column housing that the shaft goes through. The rest is easy. Simply buy pre-made U-joints such as these and bolt them together:
Replacement rack gears are very available at just about all auto parts stores and they are inexpensive. The gear I'm using is a Chevy gear and the hydraulic fittings are common A-N (army-navy) flare fittings. Only one line is high pressure, the other is 'return to tank' that uses common hose clamps. - Dave