Sounds like a carb problem dumping fuel and fouling out the plugs. It is either during WOT or idle circuit or possible a warped air horn causing air to leak in.
Want a quick solution? Take it to a carb shop and have it rebuilt, telling them exactly what you have stated about the plugs. I bet $200 will solve most of your issues. Then final tune.
I used to live in Cocoa Beach.. Will be in Miami on a layover the 23rd of Jan..
Si Vis Pacem Parabellum
1967 Starlight black PMD Engineering 400 Auto 1968 Alpine Blue 400 4 speed 1968 Verdoro Green 400 HO 4 speed 2013 1LE 2SS/RS Inferno Orange Camaro.
