I recently installed electric power steering in a 1966 Mustang. I did not use a kit, I simply pulled a column style EPS from a newer GM vehicle and then spliced the unit into the original steering column.

The results far exceeded my expectations and the cost was less than $200. I designed a controller that automatically adjusts assist level based on vehicle speed, so that the steering feel is "just right" regardless of speed.

I documented (with pictures) how I went about this on a Vintage Mustang forum. If anyone is interested do a google search for "Best $200 mod ever (EPS)"

or follow this link to page 7 where the details start:
http://forums.vintage-mustang.com/mod-c ... ost6037649

Any questions just ask.