Carbon Buildup

Have a mid 80's 454 with about 10,000 original miles. The inside of the engine is spotless with the exception of the #1 cylinder. I have not pulled the head, but the plug was heavily covered in carbon to the point of nearly closing up the gap. Exhaust port has heavy carbon builup. Inside the lifter valley there was an area of sludge built up from the block deck and head mounting surface. Anyone have any idea whats up? I'm thinking it could be...1) Bad head gasket...would that cause carbon buildup in the exhaust port? 2) Bad intake manifold gasket...sucking in oil from lifter valley? 3) Bad valve stem guide... 4) Bad valve stem seal... 5) Broken rings on piston. Any help/guidance would be appreciated.

Could be every thing you listed. Does not sound good. Could even be rings not aligned properly. . The engine has not been ran if it only has 10000 miles and is that old.

did you check the hole for compression . you are taken it apart you will fine out soon bad rings you get a lot of oil could be many things poor tune up