You don't get WET oil on spark plugs unless it's coming from outside the engine... in the 7M's case, valve cover seals and the three galley cover bolts are the only place it'll come from.
The oil inside the plenum is a side effect of a functional PCV system. Excessive amounts may point to a problem with blowby due to worn rings, a leak down test would tell you what shape the rings are in.
Automatic radiators had a small oil cooler for the transmission fluid.
http://www.cygnusx1.net/Supra/Librar...spx?F=1603&P=3
Pitting around water jackets is the result of the wrong type of coolant being used... it's due to a dielectric reaction. Thoroughly fluch your cooling system and switch to Toyota's red coolant to prevent further damage. Supposedly, the newer green coolant formulas are better at preventing this type of corrosion, but if you're already seen signs of damage I'd switch coolant soon.
NOTE: You MUST thoroughly flush the coolant system out before changing from one type of coolant to another. Failure to do so could result in emulsification.