Here’s the “conversion kit” for the 55 Thunderbird. Sit down and take a deep breath before you open it. It has all the parts required. I used one of these 20 years ago, followed by a rebuilt 3 sector (mid 56-57) box. It should give you a little better idea what you’re looking for. Notice the steering box is the same, no replacement needed.
The bird has a slightly more narrow track than the full size cars, so I expect the center link is too narrow for your use. But K might have some replacement part numbers to confirm or deny that.
The problem doing any other conversion (new power box or rack and pinion) is the steering shaft is part of the box, all the way to the steering wheel. So that has to be cut off, the column modified, the column shift reworked or replaced, etc. I can tell you from personal experience that you gain very little if anything in steering feel or ratio over the oem power steering. Unless you can do your own machine work or you replace the column with an aftermarket one it’s a bit difficult. That’s why the electric steering is attractive. And none of these alternatives are cheap, and if done cheap are probably not safe.
Due to age and old injuries I really need power steering these days to enjoy the car. So I’m sympathetic to your desire to add it. But it’s easy to go down the rabbit hole and not be able to stop digging.
https://www.larrystbird.com/product/...7-replacement/