One new EPC brand thermostat gasket, part number 49-65779 or 49-05779.  This fits:

Honda Civic CVCC 1488cc 1975 - 1979

Honda Prelude 1751cc (housing gasket) 1979 - 1982

Honda Accord 1600cc 1976 only

Honda Civic 1300 1980 - 1983

Honda Civic 1500 1980 - 1983