Hey Brad - So wait, an engine is not a grill? So I shouldn't be cooking hotdogs and hamburgers on it?
To answer your questions, the smoke starts out grayish black and builds to black smoke. I guess I forgot to mention, when I swapped in the new plugs I did do a compression test and there is no deviation between the cylinders. The new plugs (after running about 5 minutes) were black, but that was before all the carb adjustments and fuel line changes. The smoking stopped after that. However, I will admit I did not clean them or plug in new to check if they are still burning rich.

I don't believe a bent valve would be an issue, since I replaced all the valves, springs, lash adjusters, etc... about 5 years ago. Ensuring that the new valves seat firmly before re-attaching the head. The truck has not run for more than 10 min., at a time, since then due to other work I wanted to complete to get it road worthy and able to pass inspection.

I know that the exhaust manifold has been on the truck since the beginning of the work I've done. So there were exhaust valve oil leaks at one time, which lead to oil dripping into the manifold. Additionally, it has been running extremely rich since then as well.

Maybe I'll just get some new plugs again and let it run with a slight load for 10 minutes and see how they look, before making any further adjustments.