Bent pushrods and/or damaged rocker arms are all too frequent problems while attempting to wake up stovebolts from a long sleep. The pushrods in particular are pretty flimsy and it doesn't take much resistance from a rusty or sticky valve to wreak havoc on the valve train. For penetrating oil, I prefer KROIL, used liberally. Remove the valve cover and give the valve stems a generous shot, followed by manually manipulating the rocker arms several times with a pry bar before you make any attempt to turn the engine. It's expensive, but not nearly as costly as a bunch of bent or scored internal engine parts. I prefer the bulk quantities, quarts or gallons, to aerosol cans. Obviously, the cylinders need a generous shot of penetrant as well.
www.kanolabs.comJerry
