Helps if you buy the "special" tool, a thin wall socket that fits in the TFI. May not be able to get it with a regular soxket. Tool is about 6 bucks at most stores. May have to turn the distributor to gain access but do not have to remove it. If you dont have a timing light mark the dizzy with a sharpie so you can turn it back to the same place. The dieletric grease is for the eletrical connection also highly recommend heat sink compound for the tfi to dizzy mating surface.
The TFI module mounted on the distributor is usually the culprit for a high speed miss on a warm engine. If the problem does not occur when the engine is cold, the TFI module is definitely suspect. You may need a special socket to remove the TFI module, but most auto parts stores will have one for $5-$7.
Be sure to use plenty of the heat sink grease on the new TFI and clean the old grease off the distributor.