Just found this on a web site. Looks like it is not much of a difference.
The charts will give you overall height, length and width of a fully dressed engine (oil pan, intake and carburetor, front accessory drives, exhaust). These measurements are general, and can vary depending on what equipment you or the factory installed.
Chevrolet 262-400
Dimensions: 26 inches wide, 28 inches long, and 27 inches tall
Weight: 575 pounds
Sump Location: Rear
Starter Location: Right
Ford 221-351W
Dimensions: 24 inches wide, 29 inches long, and 27.5 inches tall
Weight: 460 pounds
Sump Location: Front
Starter Location: Left