I have it on my 67 (I used Bruce for the entire package from flywheel back!). It did take some getting used to, it is so smooth with very low pedal effort. I love it! I have Hooker Super Comp headers and the cable snaked right through the middle of the tubes!
The hole that you have to drill for a 67 is a bit tricky as it is on a curved part of the firewall. It is also pretty tight inside, but once you get it set up it's great. I think that Mustangs Plus says you can install it in 60 (I think Bruce says 90 minutes), but plan on it taking the better part of a day if you have to saw off the little bit on your clutch pedal (the directions have more info on this).
Let me know if you have additional questions.