An actual what? Teacher? Consider that a teksid or a new style aluminum block can handle over 1000hp I seriousley doubt you could damage the block by putting it on an engine stand. Think about the forces at work when an engine is making that kind of power at 6-7000 rpms.
Also how would you actually assemble and engie that is on a stand that holds the block from the engine mounts? All of the ones that I have seen are just cradels with wheels and do not rotate.