Any city having a population of three hundred fifty thousand (350,000) or more, but less than four hundred thousand (400,000) according to the last preceding Federal Census and having a full time regularly organized fire department and having an established municipal employees retirement plan shall be authorized to provide for the retirement of its firemen by appropriate ordinance under the terms and provisions of such employees retirement plan if the benefits provided by such employees retirement plan are substantially as advantageous as the benefits provided by Chapter 125, Acts of the 45th Legislature, as amended (Article 6243e, Vernon’s Civil Statutes of the State of Texas).
Upon adoption of an appropriate ordinance, all of the assets of the Firemen’s Relief and Retirement Fund shall be transferred to the Municipal Employees’ Retirement Fund and thereafter those persons serving as active firemen duly enrolled or contributing to the fund shall be subject to all provisions of such Municipal Employees’ Retirement Fund and the Municipal Employees’ Retirement Fund of such city shall assume all liabilities and obligations of the Firemen’s Relief and Retirement Fund at the date of transfer. Thereafter such Municipal Employees’ Retirement Fund as combined shall not be subject to the provisions of Chapter 125, Acts of the 45th Legislature, as amended (Article 6243e, Vernon’s Civil Statutes of the State of Texas).

Provided, however, nothing contained in this Act shall be held or construed to affect or impair any act done or right vested or accrued under Article 6243e, V.A.C.S., pending in any proceeding, suit, or prosecution had or commenced in any cause thereunder, be it before the courts, the Firemen’s Pension Commissioner, or the Board of Firemen’s Relief and Retirement Fund Trustees; but every act done, or right vested or accrued, or proceeding, suit or prosecution had or commenced shall remain in full force and effect to all intents as if Article 6243e, V.A.C.S., were applicable thereto and any and all liabilities existing under this proviso, be they vested, accrued or contingent, shall be the obligations of the Municipal Employees’ Retirement Fund.