Hotrod Lincoln is right on the lubes. Be sure to lube each cylinder with motor oil before installing the piston and squirt some oil on top of the rings in the cylinder when the pistion is in. Keep the cylinders lubed when rotating the engine. If it is as difficult to rotate as you say you need to be sure the cylinders are lubricated. Did you check the ring gap? I usually soak the lifters overnight or longer in a can of motor oil if they are new lifters so they don't take so long to pump up. Assembly fluid that Hotrod Lincoln was talking about is great stuff. Like a cross between snot and syrip (sorry no other way to describe it). You will know when to stop turning the oil pump with the electric motor because it will probably try to stop the electric motor.
