Yes
I replaced my 66's power steering with a Randalls Rack.
1) My stock steering need a major rebuild, it leaked from every single square millimeter. And to make things worse it tended to dart, you'd turn the wheel with little to no response then out of the blue it would grab and oversteer. It was scary. Randalls wasn't that much more than new/ reman components.
2) It is waaaaaaay more responsive and better road feel in my experience.
3) It is safer. The steering collumn now has a collapable joint in it, where as the 65 and 66 was a straight shaft hard mounted to the steering box. In a bad accident that shaft becomes a toothpick and you the olive. Now granted in an accident that bad your gonna get jacked up anyway but it is one less thing.
4) I have a 351W and my power steering pump never mounted right. Now I have a new bracket that fits properly and is smallet and light weight.
5) I have Granada front discs and was able to go with stock outer tie rods, and not have to buy the one really expensive tire rod end to get around the CV.
On the Down side.
You lose turning radius. I drive my car for pleasure, blasting up and down back country roads so I don't notice it. If I were to try and drive it in the city and to the mall constantly it may bother me. THere are things you can do to mitigate this by either re-drilling the spindle or using a bumpsteer kit to move the outer tie rod closer to the pivot point of the spindle.
You have to cut your Stock collumn. (didn't bother me)
The car is no longer stock/original (again doesn't bother me)
I've had the car now for 7 years, and wish I could have made this change years ago. I'd do it again in a heartbeat.
b