The “Retirement Systems Reciprocal Act”, being Article 20 of this Code, is adopted, and made a part of this Article; provided, (1) that where there is a direct conflict in the provisions of such Act and the specific provisions of this Article, the provisions of this Article shall prevail, and (2) that Section 20-131 shall be applicable to this system only if a participant has rendered at least 6 years of service as a member and, (3) that in the case of any participant who would have been eligible to have his or her retirement annuity computed under Section 20-131, the survivor’s annuity payable in the event of the participant’s death under Section 2-121 to the surviving spouse shall be computed on the basis of the retirement annuity to which the participant would have been entitled under the provisions of Section 20-131 if such computation would result in a greater survivor’s annuity.