Hopefully I'm not repeating what's already been said but.. The 427 SOHC has a long timing chain and ended up seeing service in drag racing, both bodied cars and fuel dragsters (Don Prudhomme, Connie Coletta, Pete Robinson, etc). The 1963 Ford Indy engine was an 255 cu in aluminum block derivative of the new "Fairlane" 221/260 production engine (forerunner of 289/302). This was a push rod engine. In 1964, they adapted DOHC cams for this engine which were gear driven. It finally won Indy in 1965, and went on to win lots of USAC open wheel races; before being effectively ruled out of service. Later, Cosworth developed an Indy engine based on the Formula One Ford engine which was a whole different thing. IIRC, they didn't bill the Cosworth engine as a Ford because they converted it for Indy use without Fords direct participation. However, you saw some of the Indy Cosworths wearing their F-O-R-D Formula One cam covers. It was interesting that the 63 Indy Ford push rod engine ran on gasoline and had carbs; and was able to finish 2nd and 7th in its first race against pure racing engines of the same displacement. Later they changed the rules to allow push rod engines to have more displacement. The Gurney engine was a Ford small block with special push rod heads (Gurney-Westlake). Later, Gurney also developed similar heads for the small block Chrysler engine.