581. Notwithstanding section 541, the revision office or review board for matters relating to the classification of industries and the assessment of employers established under section 171 of the Act respecting occupational health and safety (chapter S-2.1) is continued and preserves its jurisdiction to examine, hear and decide finally any matter or question relating to the classification of industries and the assessment of employers made before 1986 for a year preceding 1986. Notwithstanding the foregoing, the Commission may modify the composition of the office or board.