Notwithstanding any other provision of this chapter to the contrary, the board may, by a resolution adopted, pursuant to both this section and Section 31768, by a majority vote and with respect only to persons who first become members on or after the effective date of the resolution, act as follows:
(a)
Elect to increase, by 3313 percent, the amounts payable pursuant to any one or more of Sections 31781.1, 31785, and 31785.1.
(b)
Elect to decrease, by 20 percent, the amounts payable pursuant to any one or more of Sections 31786, 31786.1, and 31787.
This section shall apply only to a county of the first class, as defined by Section 28020, as amended by Chapter 1204 of the Statutes of 1971, and Section 28022, as amended by Chapter 43 of the Statutes of 1961.