Pull the plugs and add a good dose of a 50/50 mixture of Acetone and any regular ATF. 2 onces or so per cylinder and then let it set a week. Take off the stator cover and use a chuck of old belt leather and wrap the rotor with it.
Next get a pipe wrench and a length of cheater pipe ( think chain link fence post here ) and gently start breaking the engine loose. Work a little one way and switch direction. Keep doing this and add a few squirts of engine oil down the plug holes from time to time. She will let loose.
Once its turning over ok, use the shop vac and some 3/8 ID rubber tubing taped in side the shop vacsuction hose to go into the plug holes and suck as much loosened crud up as you can. Move the tubing around so as to cover as much of the cylinder as you can.
Rebuild the carbs and stick the rear end out the garage door and fire her up. It will smoke like all hellz for a while till the oil burns out of the jugs so keep a few fans blowing to keep her cool as you bake the crud out.
