The provisions of Part IV, Chapter IV, Section 1 (Withholding on Remuneration, Fees, Contract Money, or Prize Money) of the new Act (excluding the parts concerning the remuneration of professional boxers set forth in Article 204, paragraph (1), item (iv) (Obligation to Withhold Taxes) of the new Act, the remuneration and fees set forth in item (vi) of that paragraph, and the horse racing prize money received by horse owners set forth in item (viii) of that paragraph) apply to remuneration or fees, contract money, or prize money referred to in that paragraph that is to be paid on or after August 1, 1967, and the provisions then in force continue to govern such remuneration or fees, contract money, or prize money that was to be paid before that date.