Here is an Ebay auction for a pair of used complete C5OE heads by Ebay member "per1958" with a Buy-It-Now of $3,500.00 or make offer:
Here we have a pair 1966 Ford 289 High-performance head The 289 Hipo motor was the best Ford had to offer in the earlier model Shelby Mustangs and Fairlane's. The Shelby GT 350 and all K model Mustangs as well as Hipo Fairlane's all used these 271 HP motors. A stronger better design these are a Cobra must. All the Hipo characteristics are present as seen in the photos. You can clearly see the recessed valve saddles and of course factory screw in studs in the one with a 19 and one 20cast into it and it is dated Oct 27th 1966. Very nice pair of Heads. Hard to find please see photos can build a box for Shipping.
1965 1966 Shelby Mustang GT K Code 289 Hipo Head C5OE Both Are 6K 27 | eBay
-Fred-