You're right about Terry Park and Morecambe. I've got a list of players who have scored hat-tricks in the FA Cup as follows:
Joseph Hewitt - 04/12/1893 Tom Axon - 31/10/1896 Jimmy Lomax - 02/12/1911 Charlie Sargeant - 15/12/1938 Jack Connor - 22/11/1952 Jack Connor - 21/11/1953 Terry Park - 25/11/1978 Jeff Eckhardt - 11/11/1995 Will Collar - 07/12/2022