There was another thread on the inaccuracy of Persia being a theocracy and there was a suggestion that Persia have a unique government to represent the fact that the Safavid dynasty was also the head of a sufi order. My suggestion is a "Sufi Monarchy" which will allow them to have a dynasty ruling them. However this should only be for the start dates when the Safavids rule Persia. Maybe it will also have some unique religous bonuses to make the government different to a normal monarchy.