Motorcycle Repair: stuck engines, salvage yard, salvage

Question
'77 KZ1000B was running when stored 20years ago and '80 yamaha 400, not running when purchased from salvage yard, both engines seem to be seized, probably from rust, possible to soak top end in Marvel Oil to free them?  If not, appreciate suggestions

Answer
Anytime you have an engine that old and seized you really need to tear it apart and rebuild it. Not only is there rust in the cylinders but also the bearing are probably rusted and will give you trouble in the long run.
Good luck and happy riding
Mike