I was looking for this very thing so I could put my old Camaro wheels on the 63. Classic Performance Products has a kit that will convert them to a 5x5 bolt pattern.
After telling the tech what I was planning, he said that they sell "THE ONLY KIT IN THE WORLD" that would covert to a 4.75" pattern, but they require the drop spindles. Drop spindles require at least a 17" wheel.
