3options to make the RP works if you have a manual transmission
- Switch to cable clutch
- Switch to hydraulic clutch
- Modify the equalizer bar to make it work ... lots of fun but cheap and works

 

Also if you don't want to buy the Unisteer kit and are wanting to custom design something to save money there is one other option. The only OEM R&Ps that I have seen work really well in a Mustang are the center steer ones like on a GM J-car

because the original GM steering linkage mounts to the center of the rac the unit is short and will easily fit, and more importantly you can fabricate a bracket that bolts to the center section and then allows you to locate the the inner tie rod mounts in the correct location to recreate the correct original Ford steering geometry. I will be building a rac like this for my 62 Galaxie. Here is a picture of a unit, using this concept, designed by a friend of mine in Sweden. It worked so well he sold the rights to it to a company over there.

Also here is a link that may help where some one shows how they installed one in there car.
http://web.archive.org/web/200401011...e/R&P/R&P.html