Here is the vintage lever compared against a BMX brake lever's barrel adjuster. As you can see, a modern day ferule will not fit nor work with the vintage lever. The last picture is of a universal ferrule installed onto the vintage lever.
I need to find the c-clamp portion of the brake and a ferrule that will fit in these vintage levers.
-- update --
i just found a bag of the ferrules at BikeStop:
Dia-Compe 92 Steel Brake Lever End Button, for tourist levers, 5.0mm ID, Bag of 10
http://www.ebikestop.com/Items/004-br1241?
