You have to rotate the crank to get the rods into position to remove the rod nuts. Need to work on loosing up the pistons and the valves. I would start by removing the valves, removing the rods and pistons that you can, then start soaking the remaining pistons and start working them loose. A lot of this depends on what you are wanting to save. If the valves not savable, I would cut them and get them out of there and the valve springs should not be reused anyway. You might want to try and save the rods, most likely the pistons are worthless. There have been several treads on here recently on ways to remove frozen pistons and freeing up engine parts.