The Land Rover steering rack arrived from England and I have good news. It works!
I confirmed the width of the tie rods (the tie rod ends are clearly different) and guessed that the steering ratio and torque sensor would match up. I then swapped in the old brushless power steering motor since it’s programmed for the Tesla and tried it out. With the car on the lift, (no load) it feels normal so it looks like this was a success! I think it was fun to learn about the inside of the EPS system, but I’m also thankful I didn’t need to reassemble the old rack and pinion.
Cash saved: Almost $2500. Time spent: Many hours over the last month and a half. Was it worth it? Probably, who cares? It was fun.
btw: If you are looking for Model S parts like a -A 85 kWh battery, Drive unit and rear spring suspension, Charger, but not much in body parts from a 2012, let me know. There’s a salvage one I could get but it only has a few parts I need so it’s only going to be worthwhile to me if someone else can make use of the major parts.