Such sums as may be necessary for the payment by the United States of its proportionate share of the expenses of the Pan American Railway Congress and its Permanent Commission; and

Such additional sums as may be needed for the payment of all necessary expenses incident to participation by the United States in the activities thereof, including expenses of the United States delegates, their alternates, and appropriate staff, without regard to the civil-service laws and chapter 51 and subchapter III of chapter 53 of title 5; personal services in the District of Columbia; services as authorized by section 3109 of title 5; hire of passenger motor vehicles and other local transportation; printing and binding without regard to section 501 of title 44 and section 6101 of title 41; and such other expenses as the Secretary of State finds necessary to participation by the United States in the activities of the organization: Provided, That the provisions of section 287r of this title, and regulations thereunder, applicable to expenses incurred pursuant to subchapter XVII of this chapter shall be applicable to any expenses incurred pursuant to this subsection.