These are the early 221-260-289 type covers. Used in 62 and 63 on the motors that had an
oil fill tube sprouting out of the front cover rather than a fill cap on the valve cover. Shelby added the tube and breather. And yes, they fit the 351 Windsor.
Still out there at swaps and in some boneyards. Cruise the Fairlane boards and look for guys who want cast COBRA covers and do a trade! Sold my last set a while ago....
Rick