Locked Engine

My method saves the block and crank, but not the rods or the pistons.
I use a torch and cut the connecting rods which allows me to remove the crank. You can then soak the pistons in PB Blaster (from the top and bottom)and beat them out with a sledge hammer and steel pipe (I like to put the pipe over the cut off rod).

I've never had a locked up block that didn't eventually give it up.