Actually, Daoism was practised in Tang Dynasty as Laozu shares the same surname of the Tang royal family.
Besides Song Huizong, Ming Shizong is a pretty better choice than that if you don't like it. But during his reign, the Song Dynasty came to its climax: vibrant economy, new heights of literature, arhitecture, arts and philosophy, a new record of population (150 million) etc..
Ming Shizong (please attend to the spelling and make sure you won't get wrong) was a very disputed figure, go and find out more if you are interested.
Since Han Gaozu to Han Jingdi, the Han empire is practising philosophic Daoism (not in religion form), you may include it in some kind of form to finish your leaderhead.
There are extremely scarce Chinese leaderheads and I am in need, would you mind sharing your leaderhead information with me?