Wild Cobra
The 260 was initially used in the Fairlane and Falcon Sprint as well as the 1964-1/2 Mustang. Also, don't forget that it was used in the first Cobra.
About the OHC 260, there was no such engine. There was, however, an experimental OHC 289 which was built in 1965 and installed in a HiPo Mustang. I purchased this car under Ford's X-plan in Sept. '66. This experimental engine was removed and a new HiPo 289 installed in its place to return the car to its original production configuration so it could be sold. The experimental engine installed in the Mustang was one of three OHC 289's. One was in my car, another was used for dyno testing and the third one was used in engineering for reference purposes.
There was a cover story in HotRod Magazine in 1967 ior '68 that included this engine among other experimental Ford engines. As for where the engine went, probably to the great smelter in the sky as does most experimental auto parts go.
You can see this car in my gallery. I still drive it and I see to it that the car is still in the experimental phase.