[Danr55]

Tim, are you stirring because you enjoy stirring it or are you curious for real? The Cobra didn't start with Carroll Shelby. It started with AC cars of England. Shelby brought it across the pond and made it the fasted production car in America. The difference between the 427SO and the rest of the FE motors is clearances and manufacturing tolerances. The SO is in fact an FE block. Output in HP and Torque between the 427 and 428 motors, are not explained by the differences in manufacturing tolerances. There are also differences in Cam and crank shafts, head configuration, fuel delivery. It is my understanding from many sources that the majority of the production 427 cobras actually had 428 motors in them. So, while I agree that to be correct, you should use one of the Ford motors, it's your project. You do what makes your bell ring. I've often wondered what one of these cars would do with a small (345ci) Hemi motor.