One new EPC brand clutch master cylinder repair kit (made in England), part number SP2173 or SP1963.  This has a .625" diameter bore and fits:

Saab 96 09/1964 - 09/1968
Saab 95 1964 - 09/1968
Sunbeam Tiger 1965 - 1968
Sunbeam Imp 1965 - 1967
Lotus Elan 1968 - 1976
Lotus Esprit 1975 - 07/1977
Lotus Cortina 1963 - 1967
Austin Healey 3000 1961 - 1967
Morgan Plus Eight 10/1972 - 1977
Morgan Four/Four 1961 - 1966
MGA & MGA Twin Cam 1958 - 1962
MGC 10/1967 - 1969
Rover 3500 1980 - 1981
Austin A55 Cambridge 1959 - 1962
Ford Anglia 1959 - 1967
Morris Oxford 1959 - 1961