Running a stuck engine

I have an engine that is stuck. When I say stuck I mean a piston is froze in a cylinder. I was wondering if anyone has had any experience with freeing up a stuck piston and then running the engine. Did it run for a short time or for a long while. Did it smoke? Am I fooling myself with attempting to run it without a rebuilding it? The engine is a 440 and the cylinder wall has some pitting.
Thanks, Andy