I'm not going to debate the dictatorship part of your comment, but is there a islamist government (elected or not) that has been good for human rights - or any religion based government for that matter?
Keep in mind that this referenfum was organized under a state of emergency imposed after last year's failed coup. So its democratic nature is rather questionable. The No campaigners were misrepresented and harassed.
No, the Shah was pretty brutal. Besides SAVAK there were many other really bad episodes, one of which I read about some years ago but have never forgotten about as the epitome of decadency:
https://en.wikipedia.org/wiki/2,500_year_celebration_of_the_...