[jhv48]

Yes, even though it wasn't required in the 60's you will need a completely closed pcv and breather system. If you have a breather on the opposite valve cover, it must vent into the air cleaner, not the open air. Many have failed by missing this simple requirement (myself included). Just buy a cheap breather with a hose attachment. Then you must attach the proper hose (one suitable for a pcv valve, not just a fuel hose) and run it into your air cleaner base. You can buy all the parts for about $15.00 at O'Reilly auto parts. You don't want to fail and have go back for a second appointment.