See, the Early Hemi is the most misunderstood engine in the whole world of Mopardom. They ARE Small blocks. Ever wonder where the odd lifter angle on the LA engine comes from? It's direct ancestor is the Poly, and the Poly evolved from the Hemi.
The Early Hemi has the same motor mount ears, same trans bolt pattern, takes the same timing set, and oil pumps as the Small Block. As for physical block size, a Dodge is slightly smaller and lighter than an LA, the DeSoto is exactly the same size and the Chrysler is slightly larger. Think of the engine he is considering using as a long stroke, small bore LA with hemispherical heads, because that is exactly what it is!