We imposed the The Shah of Iran, who did lead Iran to a more western model of life.......However he was also a vicious dictator........
It was somewhat more complicated than that. In 1953, we helped the British drive Mohammed Mosaddegh--prime minister of Iran from 1951 to 1953. He was not a bad guy. But once we'd overthrown him, we encouraged our man, former Shah Reza Pahlavi, to return to his throne. He did so. It took him a while to become truly nasty.
And I don't think he was really evil. He was weak, and let himself be pushed around; he was also not terribly bright. The Shah of Iran you appear to be talking about is his eldest son, also called Reza Pahlavi. He seems to be a reasonably decent person, and would like to become titular head of the government, but he doesn't seem to have any money.
He says he's a friend of the U.S. and of Europe, and would make important alliances with Western democracies if the took the throne. But it doesn't really seem like that he has much of a chance.