Jawa engine rusted solid?

A while ago I bought an old Jawa as a barn find. The problem with it is the engine, mainly because the cylinders absolutely don't come off. I wanted to split the engine apart and rebuild it myself. I've already tried chemicals and soaked it in rust remover and WD40 for a couple of weeks, both to no avail. Next I just used brute force, i.e. took a suitable piece of hard wood, placed it on the piston and hit it gently at first but later just with pure force. Not a millimeter has moved there. And before anyone accuses me of this, no, the two pistons are not at TDC or BDC. I'm at a loss and am slowly starting to think that it's the crankshaft that's so rusty, because the pistons and cylinder liner don't even look that bad, considering the cylinder is so solid. My last idea would be to completely disassemble the pistons to get to the connecting rod, and then simply try to remove the entire cylinder with the piston. That would completely damage the crankshaft, but I think it's already broken anyway. Anyone have any ideas before then? Oh, and it's a 350cc Jawa, a type 354, so it has two cylinders, so that doesn't exactly make things any easier. Thanks for the help.