Rick: I don't have any data for you concerning your family history or surnames, but the use of the word "Reverend" is very common and appropriate among Catholics. In person, it is the practice to address a priest as "Father", and in the salutation of a letter, one would say, "Dear Father O'Neill". In addressing the envelope, however, as well as the heading of a business letter, the proper form is "Reverend William O'Neill". If he had been named a Monsignor, the proper envelope address would be "Very Reverend William O'Neill" or "Right Reverend William O'Neill", depending upon which kind of a Monsignor the Pope had made him. So now you know more than you wanted to about the use of the title "Reverend" by Catholics......but its use by Protestants is also very common, so you cannot tell a clergyman's specific faith by that title alone.
Neal J. Blaney, Jr. email@example.com