Bruce, I - and a whole lot of other people - often use an electric drill to spin up an engine on the bench, both for compression tests and to work an overhauled engine for a while before starting it. However I would never use a drill on a rebuilt engine that I had not turned over by hand several times first. There are two reasons for this. First, the electric drill just applies as much force as possible whenever it is resisted. This will have ugly effects if something was incorrectly assembled. The second reason is that our hands are well-trained, fine-discriminating force measuring devices. They notice that slight grittiness, occasional small changes in resistance, and various other signs of insufficient lubricant or cleanliness, misalignment, or whatever.

There is an example of what can go wrong in your post 5710 earlier in this thread. You said that the engine was hard to turn over, after assembling with new rings. Meanwhile, those rings look as if they were not oiled prior to inserting the piston into the bore, and since the rings and grooves appear dry after the engine had been turned over, I wonder if the bore was oiled either? Oiling the rings/ring grooves and the bore is essential. If you do not, the rings are likely to be scuffed, as your lower ring seems to be, in the first seconds of the engine's life. This greatly shortens their life.