I think the big Ford six was built for more years than any other Detroit production motor. It was never designed for high performance, it won't fit into most Ford passenger car models because it's so long. Other than EFI I do not know how Ford might have improved this venerable series over the years.
The only complaint I've heard about the 300 is the fuel economy is often not better than a small block V8. Its a classic work horse motor.
