As you have seen 7 of the 8 plugs are dull and dry, the shiny one probally has oil on it Now to figure where the oil is coming from, does the PCV, positive crankcase valve, feed into the number seven intake runner? If not try removing the carb. from the intake and look inside the manifold to see if you can see where the oil is coming from If it is not coming in the top of the intake manifold then it may be sucking oil through that intake valve seal or that intake port intake manifold gasket The last thing I could think of is a stuck set of piston rings but the compression test and the spark plug not fouling tells me that is probally not it Let us know what you find