Here's an update for everyone. After replacing the stem seals from the umbrella-style to the newer press-on style, my problem fouling plugs persisted. As a last ditch, i replaced my (brand new!) ignition coil with yet another and the problem went away. So basically, my stock coil was fried, and the brand new 1.5 ohm accel coil I replaced it with was also bad. Coil #3 did the trick. The coils are mounted in the factory location, horizontally with the factory bracket, with a factory .5 ohm resistor. Apparently they don't make them like they used to.
I have put the stock needle springs back in the carb, reset my idle air mixture and advanced the timing back to where it was. Car is running very well. Hopefully it will make this 1100 mile road trip tomorrow safely. I have a spare coil and all my tools.
