Any person who was serving as messenger or doorkeeper of either house of the General Assembly on January 8, 1973, and who was a member of the retirement system on that date shall:

(1) Acquire the same rights and credits in the same manner and under the same conditions; and

(2) Be authorized to make contributions to the retirement system in the same amounts, in the same manner, and under the same conditions,

as would a member of the General Assembly under the Georgia Legislative Retirement System.