What to with a fresh rebuilt motor that has been sitting 3 years?

I'd turn it over slowly by hand after the PB soaking for a few days; start easy. If it won't start turning with a pretty low level of torque , then let it set for a while more with more penetrant added. The idea is to make sure that a ring is not rusted stuck and to get it loosened easily so it does not break or break a land.