Tom,
Sounds like you are getting things sorted out and have a game plan, which brings me to my next question, which I know is WAY late..
Have you ever driven a Cobra without P/S? My casual observation is that the P/S setup is lots of extra work and headaches on these cars. I can honestly say, having driven both P/S and non P/S. I prefer the non. Even with my heavy 460, my car steers wonderfully with a manual Flaming River rack. Something else to keep in mind, if you ever plan to autocross, in a tight course, you will most likely out drive, or, be "ahead" of your production car type P/S system, which is a real pain in the a$$. I experienced this with a '90 5.0 Mustang that I autocrossed some.
Anyway, I know this is way late, I just wondered if you considered manual steering at all, or drove a Cobra with manual steering.
Good luck getting your car together! Sounds like you are getting close!
Dave