I have the RARE 2.5" versions on my '64 so that I could run 2.5" exhaust to it's full advantage, but they currently show that they are out of stock. You could contact Ram Air Restorations to check on when they'll have them back in, but they do have the standard (2.25" units) in stock:
https://www.ramairrestoration.com/rm...y-headers.html