I've been marinating a stuck Cadillac 390 for 5 months now. Cylinders filled with Acetone and ATF. Pulled distributor, rockers, push rods and timing chain. Cam and rotating assembly good and stuck. Rings must've been fine as the cocktail doesn't run past very fast. Other than patience, what else could help? Thinking about building a device to hold a porta power and gently press the pistons down with the crank out. No rust on the bottom end from what I seen with the pan off.