There is reference to, Sylvester Radcliffe in the book,

Ramsey 1600 - 1800 by Constance Radcliffe

Black - pages 110 - 113, under Ramsey people

John Black 's second wife was, Grace Cook an English woman

you can request this information at the Manx look up exchange.

also, Will of Elizabeth Black first wife of John Black, can be seen on, Manx notebook

1659 Archdeacon Will # 65 Maughold
Hope this helps,
Averil