What gas engine interchanges with a 7.3 power stroke?

There is no direct gas engine interchange with a 7.3 Power Stroke diesel. The 7.3 Power Stroke is a unique engine with its own distinct mounting points, bellhousing pattern, and ancillary components. Gas engines are designed differently and are not physically compatible. You would need a complete frame swap and extensive modifications to even attempt such a conversion, and it would likely be a very costly and impractical project.