Where, during the transitional period, a contributing member (whether an existing contributor or not) retired and, on his retirement, became entitled to invalidity benefit under Part V, any classification of the person during the transitional period by the Board purporting to be under section 51 of the previous Act shall, for the purposes of this Act, be deemed to be a classification of the incapacity of the person by the Authority under section 30 of this Act, and any reclassification of the incapacity of a person during the transitional period by the Board purporting to be under section 53 of the previous Act shall, for the purposes of this Act, be deemed to be a reclassification of the person made by the Authority under section 34 of this Act.