i NEVER take apart an old unused engine.  I have had old engines unused 20 years with congealed castor oil that have frozen the engine.  I simply pour fuel in a bowl and soak the engine in the fuel overnight.  They are free the next day.  May have some bump in the bearings, but after soaking, I turn the engine over a few times, take the backplate off and wash out the congealed bearing debris left in the crankcase.  When you take it apart you have to break it in again, especially with ringed engines.