(2) That portion of the pension provided pursuant to the provisions of this section which is in excess of the pension that the member would have received had this section not been in effect shall not be included in computing any pension reserve payable pursuant to the provisions of section sixty of this chapter. b. A member of the retirement system not in the employ of the state on April first, nineteen hundred sixty-nine, who thereafter enters or reenters such employ, shall not be entitled to have his retirement allowance computed pursuant to the provisions of this section unless:

(1) Such member renders five or more years of service in the employ of the state after March thirty-first, nineteen hundred sixty-nine and retires from such employ, or

(2) Immediately prior to service with the state, service was rendered while a member of a retirement system maintained by the state or a municipality thereof, operating on a sound actuarial basis and subject to the supervision of the department of financial services of this state, in a plan which provides service retirement benefits equal or superior to those provided under this section and at the date of his retirement such member would have been eligible for such benefits had he not separated from service with such employer. c. A member eligible for a vested retirement allowance pursuant to the provisions of section seventy-six, who separates from the employ of the state on or after April first, nineteen hundred sixty-nine with twenty-five or more years of total service, and who would have been eligible to have his retirement allowance computed pursuant to the provisions of this section had he at the time of separation attained age fifty-five, shall at the time he becomes eligible to receive the vested retirement allowance, be entitled to have such allowance computed in the manner prescribed by this section. d. In addition to the retirement allowance provided pursuant to the plan set forth in section eighty-nine of this chapter, a member of such plan who retires on or after April first, nineteen hundred sixty-nine with more than twenty-five years of total service shall be entitled to receive, in addition to the benefits provided pursuant to section eighty-nine and notwithstanding the limitations of such section, an additional retirement allowance for such years of service rendered in excess of twenty-five. The additional retirement allowance for such additional years of service shall be computed as if such member had been eligible to have his retirement allowance computed pursuant to the provisions of paragraph one of subdivision a of section seventy-five-c and of paragraph one of subdivision a of section seventy-five-d of this chapter. e. The benefits hereinabove provided shall be payable unless the member would otherwise be entitled to a greater benefit under other provisions of this chapter, in which event the greater benefit shall be payable. f. In the case of persons who last became members on or after July first, nineteen hundred seventy-three, the provisions of this section shall apply only to those retiring or separating in vested status from state service prior to July first, nineteen hundred seventy-four.