the provisions of the Act and regulations specified or referred to in Part I of Schedule 2 to these Regulations shall apply for the purposes of the Northern Ireland Act as they apply for the purposes of the Act, subject to the modifications relating thereto specified in Part II of that Schedule;

any reference in the Act to any provision of the system of national insurance established by the National Insurance Act 1965 shall be construed as including a reference to that provision as modified or adapted by any reciprocal arrangements between the two countries together with the provisions of any regulations for the time being in force in Great Britain giving effect to the provisions of any such arrangements.