I am concerned with you description of the oil ring - the ones I have fitted come in 3 parts : 2 scraper "flat" rings and a "top hat" mounted on its side that locates the other two. Fitted correctly there should be no excess length, unless you were given the wrong ones...
As for turning the engine by hand, a long wrench sounds about right. The starter acts using the "lever length" provided by the flywheel and produces 6kW (assume 600A and 10volts...). Once I had engines re-built ready to start then I would spin the engine without sparkplugs until the oil pressure light goes out or oil pressure shows on the gauge (you can fit one temporarily).
A note here, a common error is to lubricate the surface of the bearings as they are fitted but the wrong surface : the bearing surface that touches the block must be fitted dry and clean. The surface that mates with the crankshaft bearing needs to be lubricated. I used to use graphogen as it stays still during the rebuild process and does not drain away as oil does. Also, it does not spoil the oil, but I would do an "early" change on a rebuilt engine.