From: Rabbi Moshe Sofer
To: Rabbi David
The Chasam Sofer emphatically denies having ruled that pidyon haben may be given to a Kohenes or her Israelite husband, clarifying that his remark at a feast was purely theoretical. He rules that the Rosh, Ra'ah, and Tur hold a Kohenes is excluded by the phrase 'Aharon and his sons,' and that informal theoretical remarks may not be acted upon. In a genuine emergency where no male Kohen is available, he permits giving the money to a Kohenes without a berachah and with a conditional stipulation.
Source: Shu"t Chasam Sofer YD §301