Thanks for checking that out for me. For now I do have an extra engine and tranny for the truck sitting in the back of a parts truck that came with the one I purchased. It's been sitting for 5 years plus in an open truck box, so it should be an adventure.
I made a mistake in my first post. I said 1200cc earlier, but these little 4-bangers are 660cc. I believe the 1200cc engines were only mounted in a few styles of Sambar that actually had a slightly larger body (marketed to Europe). I really don't want to mess with trying to cut and weld a hole for the engine, but I'll bet it will bolt to the transmission pretty easily.
Here is what an article on Wikipedia says about these models and the Justy engine, "The Sumo shared many characteristics with the Sambar, except it had extended front and rear bumpers and a larger engine borrowed from the Subaru Justy." They didn't mention that the Sumo styled vans were also a few inches wider. Also, an extended rear bumper would allow for more engine room as I open the bumper of this truck to access half of the engine.
Changing out the engine for a different one may not be a road I should tempt myself to go down right now. It would be nice to have more than 40 hp though.