How do you build a 500 horsepower Ford 390?

To build a 500 horsepower Ford 390, start with a strong foundation by selecting a robust block and using forged internals, including pistons and connecting rods designed for high performance. Upgrade the cylinder heads with high-flow options, and use a performance camshaft to optimize airflow for increased power. Install a high-performance intake manifold and carburetor or EFI system to ensure adequate fuel delivery, and consider adding headers and a free-flowing exhaust system to enhance exhaust flow. Finally, ensure proper tuning and cooling to maintain engine reliability at high outputs.