It shall be lawful for any trustee or other person having the custody of any deeds or documents, which in the opinion of the Minister of Finance are fit to be deposited in the Public Record Office of Northern Ireland, so to deposit the same with the permission of the Minister of Finance, and subject to any rules to be made under this Act, in a repository which may be provided for that purpose in the said Public Record Office, and any deeds or documents so deposited shall be deemed to be Northern Ireland records in the custody of the Minister of Finance.