(1) While the incapacity for work resulting from a personal injury is total, the employer shall pay, or cause to be paid as provided in this section, to the injured employee, a weekly compensation of 80% of the employee's after-tax average weekly wage, but not more than the maximum weekly rate of compensation, as determined under section 355. Compensation shall be paid for the duration of the disability. The conclusive presumption of total and permanent disability shall not extend beyond 800 weeks from the date of injury and thereafter the question of permanent and total disability shall be determined in accordance with the fact, as the fact may be at that time.

    (2) A totally and permanently disabled employee whose date of injury preceded July 1, 1968, is entitled to the compensation under this act that was payable to the employee immediately before the effective date of this subsection, or compensation equal to 50% of the state average weekly wage as last determined under section 355, whichever is greater.

    (3) If an employee who is eligible for weekly benefits under this act would have received greater weekly benefits under the prior benefit standard of 2/3 of average weekly wages, subject to the maximum benefits which were in effect before January 1, 1982, then the employee shall be entitled to such greater weekly benefits, but not at a rate exceeding the maximum rate in his or her dependency classification under such law. This subsection does not authorize payment to an employee according to any schedule of minimum benefits, except those provided in section 356.