BurbMan it takes very, very little oil to foul a plug. It really only takes a few drops of oil to do this to a plug. I have a turbo street motor that burns very little oil. I knew the guides were junk but I ran it anyway. The plugs looked worst than yours in 15K miles. No big deal. I would pull the plugs about every 6 months or so and "clean them," pop them back in and off I would go.
Big blocks burn oil. It's just the nature of the beast. (long stroke, short skirt piston engines are even worse) Big blocks wear guides. It's just the nature of the beast.
In fact, under warrantee, Chevy would tell you to get lost unless the engine burned more than 1 qt/600 miles. And this is BRAND NEW engines.
Your engine is fine. Just change your plugs every once in a while, and go on vacation.
