Every safety member under age 55 years and every other member under age 65 years who is retired for non-service-connected disability and who is retired simultaneously under a disability retirement allowance from the Public Employees’ Retirement System or a retirement system established under this chapter in another county shall receive a retirement allowance equal to the greater of the following amounts:

1. (1) The sum to which he would be entitled as service retirement; or
2. (2) A sum which shall consist of:
3. (a) An annuity which is the actuarial equivalent of his accumulated contributions at the time of his retirement, and
4. (b) If, in the opinion of the board, his disability is not due to intemperate use of alcoholic liquor or drugs, willful misconduct, or violation of law on his part, a disability retirement pension purchased by contributions of the county or district, all computed as provided in Sections 31727 or 31727.2.